London Underground (LU) has blamed a firm responsible for the maintenance of the Tube for delays to the network caused by heavy snow fall.
Many people were forced to walk due to the Tube delays
Metronet had not carried out necessary work overnight such as using special trains to clear snow and ice from tracks, an LU spokesman said.
Six Tube lines and 40% of Network Rail services into London suffered delays or cancellations on Wednesday morning.
Metronet strongly refuted LU's claims and said they did run de-icing trains.
Following the delays, a LU spokesman said: "Cold weather and a threat of snow were forecast and Metronet chose not to undertake the necessary prevention work overnight.
"Metronet chose to carry on with regular engineering work. This failure to deal with the forecast cold weather led directly to much of the problems on the Tube.
"This echoes their failure to prepare the tracks for hot weather last summer and is completely unacceptable.
"This morning's problems on the Tube are a clear example of poor planning and execution of maintenance by Metronet."
But Metronet spokesman said: "It was, in fact, LU who deemed the risk of severe weather to be small.
"Instead Metronet upgraded the risk level on the north and west of the network and ran de-icing trains all night, abandoning all engineering work other than essential track inspections."
Passengers experienced serious delays on the Central and Jubilee lines because of weather-related faults at Hainault and Neasden respectively, while the East London Line was suspended earlier because of multiple signal failures.
Weather also caused disruption on the District Line west of Earl's Court and some delays on the Piccadilly Line, also west of Earl's Court where trains travel above ground.
There were also minor delays on the Victoria Line.
The director of operations for Network Rail, Robin Gisby, admitted rail services were not prepared for the snow - 40% of services into London were delayed or cancelled
"We should have done much better, we had a lot of people out last night. We've got 5,000 to 6,000 sets of points that affect commuters coming into London," he said.
"We had about 90 not working in the small hours, and about 70 of them, I'm afraid to say, not working at eight in the morning."
He said more teams would work overnight as more snow was expected, and said he believed the services would be much better on Thursday morning.
Trains were mostly affected by frozen points. Mr Gisby said point heaters would be checked and empty trains run ahead of services to check for any problems.