However, protesters late Tuesday blocked roads near the Finance Ministry and surrounded more than 10 police vans that had stopped at a nearby gas station. The standoff extended past midnight.
Protesters accuse Yingluck, who took office in 2011, of being a puppet controlled by her brother.
She fought a two-front political war on Tuesday, fending off sharp criticism during a parliamentary no-confidence debate, while protesters besieged several more ministries.
She called for calm and offered to negotiate with the protest leaders.
"If we can talk, I believe the country will return to normal," she said. She has vowed not to use violence to stop the protests.
Demonstrators surrounded the Interior Ministry and then cut electricity and water to pressure people inside to leave. Security personnel locked themselves behind the ministry's gates, with employees still inside. The transport, agriculture and tourism ministries were also closed Tuesday because of the presence of protesters.
The anti-government campaign started last month after Yingluck's ruling Pheu Thai party tried to pass an amnesty bill that critics said was designed to absolve Thaksin and others of politically related offenses and allow him to return home. The Senate rejected the bill in a bid to end the protests, but the rallies have gained momentum.
On Sunday, more than 100,000 anti-government demonstrators staged the country's biggest protest in years.
In 2010, about 90 people were killed when a Democrat Party-led government ordered a military crackdown on Thaksin's "Red Shirt" supporters who were occupying parts of central Bangkok. This week's occupation of ministry offices has raised fears of violence and worries that Thailand is entering a new period of political instability.
Suthep has rejected new elections, which the now-opposition Democrats are certain to lose. In a speech Tuesday to followers at the Finance Ministry, he called for a change of the country's parliamentary system.
"If we take down the Thaksin regime tomorrow, we will set up a people's council the day after tomorrow," he told the cheering crowd. "Let the people's council pick a good man to be the prime minister, good men to be ministers. Make it a dream team, make a Cabinet of your dream and the people's government."
Akanat Promphan, a protest spokesman, earlier said the offensive to seize government offices would be extended nationwide on Wednesday. The anti-Thaksin movement is strongest in Bangkok and the south, while Thaksin's many supporters in other areas might challenge the protesters, raising another prospect for violence.
Separately Tuesday, the Democrat Party launched a parliamentary no-confidence debate against Yingluck. They accused her administration of corruption and called her an incompetent puppet. The vote has no chance of unseating Yingluck as her party controls the House of Representatives.
The protesters' takeover of government offices has drawn criticism from the United States and the European Union, which issued a statement Tuesday calling upon "all concerned to avoid escalation and to resolve differences through peaceful means".
Q: What are the protests in Thailand's capital about?
A: The protesters in Bangkok oppose former Prime Minister Thaksin Shinawatra, who was ousted by a military coup in 2006 after being accused of corruption and disrespect for the country's constitutional monarch, King Bhumibol Adulyadej. They consider current Prime Minister Yingluck Shinawatra, Thaksin's sister, to be his proxy while he remains in self-imposed exile to avoid serving a two-year jail term for corruption. There have been several rounds of protests and clashes involving Thaksin opponents and supporters since the coup, but the current unrest is Yingluck's most serious challenge since she took office in 2011.
Q: What do the protesters want?
A: They want to topple Yingluck and her ruling Pheu Thai party, but protest leader Suthep Thaugsuban said that won't be enough.
On Tuesday night he called for establishment of a "people's council" to pick a new prime minister and Cabinet. Thailand currently has a parliamentary system under a constitutional monarchy.
His proposal is similar to that promoted in 2008 by the anti-Thaksin Yellow Shirts - the People's Alliance for Democracy. They sought to have fewer lawmakers directly elected and more appointed by the country's political elite.
Q: What are the protesters' tactics?
A: After some large demonstrations, the protesters, closely linked to the opposition Democrat Party, have taken over several government offices this week. The tactic is similar to those used in past protests in which Thaksin foes took over the prime minister's office and even Bangkok's two airports.
The tactics pose a challenge to authorities who risk losing face and the control of the situation by allowing offices to be occupied, but risk alienating public opinion if they use force to dislodge the protesters. Police have made a massive show of force around critical would-be targets, but protesters have entered more poorly guarded offices.
The Democrats, meanwhile, are leading a no-confidence debate in parliament this week and are petitioning the courts and independent state agencies to have ruling party lawmakers ousted for alleged violations of the law.
Some elements probably hope that the situation becomes chaotic enough to serve as an excuse for the army to intervene, as happened in 2006.
Q: Is it safe to visit Thailand?
A: Popular resort areas have not been affected. Visitors should avoid protest areas. The Thai Foreign Ministry said Tuesday that 23 countries, most of them European, have issued travel warnings or notices about the political situation.
Q: What are the protesters' complaints?
A: They accuse Yingluck's government of corruption and abuse the power.
Yingluck and her Pheu Thai Party won an absolute majority in the 2011 election, and have used their position to railroad several measures through parliament, shortcutting ethical and legal procedures.
Corruption has been a problem under every Thai government. Thaksin, a billionaire who owned a telecommunications empire, was ensnared in several conflict of interest accusations. Criticism of Yingluck has focused less on personal corruption and more on her policies, including her support of a broad amnesty bill that would have allowed Thaksin to return to Thailand without serving jail time.
Q: What's behind the long-running political conflict?
A: Thaksin remains popular in Thailand's less well-off rural areas, where voters were grateful for populist programs he instituted, such as virtually free health care. Pro-Thaksin parties easily won the two general elections held since the 2006 coup. But his opponents still have influence, particularly in the courts and the military.
Thaksin's supporters claim that Thailand's traditional ruling elite oppose him because they risk losing influence to a popularly elected leader. Thaksin's foes have suggested that the democratic system is flawed and that the elite should have a greater say in administering the country. They are uneasy at what will happen when 85-year-old King Bhumibol leaves the scene.
- AP
