Commuters on one of Britain's busiest commuter rail routes faced massive delays today after it was closed by a trackside fire.

The line was closed as a precaution as fire crews tackled the flames at a clothing warehouse in New Cross, south-east London.

The warehouse backs on to the main line from London to Kent and East Sussex.

The blaze put the brakes onto dozens of rail services into London Bridge, Cannon Street and Charing Cross stations, affecting travellers' journeys into work from Sussex.

A spokeswoman for Connex South Eastern, which runs train services from Sussex into the capital, said part of London Bridge station had reopened and was accepting trains from Hastings and Tonbridge by 9.30am.

She said the company's north Kent services had been most affected by the line closure.

She said: "It has been terrible. There is a fire at a factory in New Cross and the north Kent line has been closed.

"The fire brigade are still dealing with the fire so it is difficult to say how long it will be closed for."

She added: "The situation is changing all the time. The Greenwich line could be closed all day."

A spokesman for South Central, which runs services from the Brighton area into London, said none of its services had been affected.

Many rail travellers who were affected had to sit on trains which could not enter London Bridge, Cannon Street or Charing Cross and many other services were subject to lengthy delays.

By 10am the three stations were reopened but operators were trying to clear the backlog of delays.

The spokesman for Connex South Eastern, which runs trains from the Hastings area through Sussex and into London said: "Services are badly affected.

"We're hoping they can get the problem sorted in time for this evening.

"There are severe delays, but the situation keeps changing."

Anyone planning to travel by rail is asked to telephone 0845 7484950 or log onto the Connex web site at www.connex.co.uk