Fears have been raised by union leaders and MPs over plans which they say would relax minimum fire safety standards on London Underground (LU).
Thirty one people died in the King's Cross station fire in 1987
A committee of MPs is to discuss rules brought in after the King's Cross fire in 1987 in which 31 people died.
Labour MP John McDonnell said a new fire safety order being considered would remove minimum standards.
But the government says it is wrong to suggest the proposed changes would "compromise safety".
The regulations being discussed lay down minimum Tube staffing levels and fire precaution measures.
Mr McDonnell said the order would allow LU managers to decide what fire safety measures were necessary.
Bobby Law, London organiser of the Rail, Maritime and Transport union said: "Passengers will be horrified to learn that the government is considering relaxing fire safety standards on the Tube.
"We hope that both ministers and the mayor of London will act to ensure that statutory minimum safety standards and staffing levels are maintained and not left to the whims of LU management."
But an LU spokesman said Tube safety was its top priority and it would do nothing to reduce safety standards for Tube passengers.
He added: "The Tube has a very good safety record. Since the Kings Cross fire in 1987, London Underground has worked extremely hard to make the Tube even safer.
"There have been no major incidents involving fire and passengers on the Tube since then."
The plans are being scrutinised by the House of Commons Regulatory Reform Committee of MPs.
A spokesman for the Office of the Deputy Prime Minister said: "The proposed changes will ensure fire safety standards are maintained.
"This will be achieved through a risk-based approach that is legally enforceable by the fire and rescue authority."