The US Environmental Protection Agency has told several lawmakers it aims to end its freeze on grants and contracts late Friday, congressional aides said.

The freeze had led to widespread concerns in states and cities about whether there would be delays in efforts to monitor and clean up toxic pollution, particularly lead pollution in drinking water, that would put the health of citizens at risk.

President Donald Trump's administration on Monday had asked the EPA to temporarily freeze grants, contracts and interagency agreements pending review.

The EPA allocates $4 billion worth of contracts annually to projects ranging from cleaning up polluted industrial sites to testing air and water quality.

The concerns were acute in Flint, Michigan, where children for years have been exposed to dangerous levels of lead in drinking water. After three Michigan lawmakers, including Rep. Dan Kildee, wrote to President Trump asking whether programs would be delayed, the EPA told them that grants to clean up the water would be uninterrupted. Congress last year approved $100 million to clean up the water in Flint.

But Flint and other cities exposed to lead poisoning remain concerned about testing.

"The people of Flint also rely on other EPA contracts to conduct independent water testing and provide expertise when it comes to ensuring water quality," said Mitchell Rivard, a spokesman for Kildee, who was waiting for the EPA and Trump to indicate whether those programs would be affected.

An official from another Midwestern city that has suffered lead poisoning said on condition of anonymity that local politicians had asked the EPA if programs would be slowed down and that they had received no answers.

A former head of grants at the EPA said the freeze was troubling because it showed a "total lack of communication about it with states, tribes, and communities."

"They're supposed to be EPA's partners in keeping people safe and healthy, so they should have been consulted, or at least warned," said Karl Brooks, a former acting assistant administrator at the agency.

If every polluted community has to push politicians to write letters to the EPA, the agency "will be spending most of its time answering congressional letters and not getting lead out of water or mercury out of our air," Brooks said.