Connex was stripped of its south east franchise in June 2003

The RMT said it was "astonishing" the government had not considered South Eastern Trains staying publicly owned.

South Eastern Trains took over from Connex after it was stripped of its franchise in June last year.

RMT general secretary Bob Crow said after Connex the "last thing" the public wanted was more privatisation.

Here they are privatising a franchise all over again. Bob Crow, RMT general secretary

He said Connex had lost its franchise last year because it had cost a fortune and allowed services to get worse.

"The government has always said that the Tories were to blame for privatising the railways in the first place," he said.

"But here they are privatising a franchise all over again when they have the chance - and already have the power - to keep it in the public sector."

The union has suggested that a South East Regional Transport Authority should be set up and that 29 MPs have signed an early day motion calling for the franchise to be kept in the public sector.

The Strategic Rail Authority has announced that four bidders will compete for a new franchise to provide services to Kent, south east London and parts of Sussex from early 2005.