The GBU-28 (Guided Bomb Unit) and GBU-37 bunker busters are designed to burrow 6m to 30m into the ground before exploding.
Planes and cruise missiles pounded Kabul airport yesterday in the heaviest bombardment since the raids began. Ten people, including women and children, were killed when a missile hit a home, the Afghan Islamic Press reported.
The Peshawar-based news agency said at least 76 people have been killed and 100 injured.
Opposition forces are urging the US to attack front-line Taleban troops massed 40km north of Kabul.
"If the Americans would bomb we could set out at 8 am and be in Kabul by noon," said Colonel Mohammad Nodair, who commands 700 men in the Northern Alliance.
But the US is wary about backing the mainly ethnic minority forces, tainted by the rape and mass murder that followed the mujahideen victory over Soviet forces.
Pakistan military ruler General Pervez Musharraf has warned Western leaders against imposing a new regime on Afghanistan, saying any post-Taleban government must be broad-based.
British Prime Minister Tony Blair yesterday suggested turning Afghanistan into an international protectorate, which would work towards establishing such a broad-based government in Kabul.
The process, under United Nations control, could take five to 10 years and cost billions of dollars.
Mr Blair publicised his proposals during a diplomatic mission to assure moderate Arab states that the war against terrorism was not a campaign against Islam.
As he quashed speculation that Iraq could be next on the allies' hit list, the Bush Administration said it would pursue bin Laden's al Qaeda network wherever the trail led.
A team would go to the Philippines to help battle guerrillas linked to al Qaeda by US intelligence officials, the New York Times said. Operations could extend to Malaysia and Indonesia as well.
In Qatar, a statement from the Organisation of the Islamic Conference urged the US and Britain to avoid civilian casualties.
A Gulf official said: "It is meant to send a signal that we tacitly approve the strikes and distinguish between the Taleban, who are smearing Islam's image, and the poor Afghans."
Map: Opposing forces in the war against terror
Afghanistan facts and links
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