Kensington and Chelsea Borough Council is under fire for failing to carry out a deep clean of ventilation systems in homes around the disaster site.
The Commons environmental audit committee has stepped in, after hearing evidence that scientists have discovered the hazardous material.
“It is astonishing that nearly two years after the fire at Grenfell, there are still questions to be asked about a clean-up to deal with the threat of contamination from toxic chemicals,” said Mary Creagh, the committee’s chairwoman.
The warning comes almost two years after the blaze that killed 72 people and criticism that the government has “done nothing” since to address the concerns of local residents.
Ms Creagh added: “Kensington and Chelsea Borough Council must provide answers to evidence, discovered by scientists, of hazardous material in homes around the Grenfell site.
“People whose lives have been blighted by the tragic events of that night should not be kept waiting for those answers”
The Labour MP said her committee had been told that fire debris, such as charred insulation, had been found inside nearby flats.
She pointed out that neighbouring Hammersmith and Fulham Council was testing soil samples, adding: “We want to know why Kensington and Chelsea is not taking action.”
But the council hit back, insisting “testing and sampling is underway” and that experts believed “the risk remains low”.
It also said the testing programme for the Grenfell site was led by the housing and local government department, in collaboration with and the government chief scientific advisor.
“The government and Public Health England have assured us that they believe the risk remains low,” said Elizabeth Campbell, the leader of Kensington and Chelsea Council
“Testing and sampling is underway. We are told that scientists will need time to analyse results and develop a programme that is both comprehensive and gives the community the necessary reassurances.”
Ms Campbell urged “anyone who is concerned to speak to their GP straightaway” to “arrange for enhanced health checks to be carried out”.