Both sites had been recently subject to live video audits by Chinese Customs.
Both had been complying under New Zealand's alert level 1 protocols, Collins said.
Updating the situation to the Herald, Collins in a statement said: "Officials have had constructive engagement with their counterparts in China and we'll continue to work with them."
The statement didn't elaborate.
China is New Zealand's biggest seafood export market, closely followed by the US and Australia.
Industry organisation Seafood NZ said exports to China in 2019 returned $713 million, up from $597m in 2018. However, more recent Government figures put the value at $400m in the year to October 2020 after the impact of Covid on China's hospitality and retail sector.
Greenshell mussel exports to China earned $337m in 2019.
Sanford acting chief executive Andre Gargiulo told the Herald the NZX-listed company operated all its facilities to the highest standards of food safety.
"We have been adhering to New Zealand's Level 1 protocols for processing and had put in place further requirements for the Chinese market. We are working closely with MPI to find a way forward."
Sanford told the NZX in a statement this week it did not anticipate a material impact on its operations or sales from the suspension of exports from its Havelock plant to China.
Sealord chief executive Doug Paulin said the company was working closely with MPI and other Government officials to resolve the situation, which was around the interpretation of the World Health Organisation's Covid-19 guidance, and food safety management.
"Sealord operates all our facilities at the highest standards of food safety, passing all previous audits. We have in place additional protocols for China. Sealord won an industry Seafood Star Award for its Covid-19 response including implementation of strict hygiene and safety measures.
"At this point in time, there is little material impact for Sealord, however it is important for this to be resolved for the future. We await the outcome of discussions between Government officials and their counterparts in Beijing," Paulin said.
MPI's Collins earlier this week said New Zealand had taken strong measures to prevent the spread of Covid-19 and did not have community transmission.
"This includes our strong hygiene measures put in place by food manufacturers and exporters, which adapt to each level of risk according to our Covid-19 alert level.
"It's important to note that the WHO's guidance says it's highly unlikely that Covid-19 can spread by food or packaging."