The boss of Transport for London has apologised after claiming the Southeastern train firm was "sh**" and its ticket inspectors were sometimes like the Gestapo.

Sir Peter Hendy wrote to the boss of the Go-Ahead Group, which owns Southeastern, apologising for his remarks about the train firm, which runs services from Kent into London.

It follows an interview with Management Today earlier this month, in which Sir Peter said: "On Southeastern the trains are like the Wild West.They are ----, awful.

"And then every now and then some people who look like the Gestapo get on and fine everyone they can. It doesn't improve your day, does it?'"

Sir Peter, who is in charge of the capital's public transport network, was speaking as Southeastern battled delays and cancellations during multi-million pounds work to transform London Bridge station.

But, just days after the controversial remarks were published, he has written to David Brown, chief executive of the Go-Ahead Group, and David Statham, managing director, to apologise to all employees for the remarks.

He said: "I am quoted in Management Today being offensive about Southeastern trains and its staff. My comment is unjustified and excessive and I apologise.

"I know everyone there is doing their best to offer a good service in the context of the franchise you have and the infrastructure you operate on.

"If there is a context, the interview was several weeks ago during the worst of the issues at London Bridge. But that's not an excuse. Passion is no excuse for insult. Sorry."

But, at the time, commuter groups agreed with many of Sir Peter's remarks.

"I am quoted in Management Today being offensive about Southeastern trains and its staff. My comment is unjustified and excessive and I apologise" - Sir Peter Hendy

Andrew Stott, of the Sevenoaks Rail Travellers Association, said Southeastern compared badly against TfL on many measures.

He said: "In the Which? survey published in February Southeastern were the second worst Train Operating Company, and only just above Thameslink.

"TfL do much better, despite having to contend with some of the problems of high demand in the London area and of Victorian infrastructure that Southeastern and others plead in their defence.

"The ticket inspectors can also certainly be over-zealous at times – we have had reports of customers being fined simply crossing the footbridge at Sevenoaks to get to the ticket office, even though they had clearly been nowhere near the platforms or the trains.

"The same goes for barrier staff at some London stations (though not at Sevenoaks itself)."