High speed trains were cancelled and delayed on the third day of the full service.

Several services leaving St Pancras International for Ashford and other Kent stations were disrupted after one train ended up stuck in a tunnel last night.

Southeastern spokesman Jon Hay-Campbell said: 'We believe that the train may have been unable to draw power while in the tunnel but we are still investigating.'

The train was stranded near the London station just after 6pm. Another train was needed to help move it.

Services leaving St Pancras now confirmed as cancelled were the 1810 to Ashford, Folkestone and Dover, the 1818 to Ebbsfleet, the 1825 to Broadstairs and the 1848 to Ebbsfleet.

Southeastern said high speed services in and out of London were affected throughout the evening with several journeys delayed.

The company put up posters explaining and apologising for the delay in affected stations.

The long-awaited full high speed service between London and Kent had begun on Sunday following limited preview service in the preceding six months.

It had been launched with major celebrations at St Pancras on Monday involving Olympic champion Dame Kelly Holmes and Prime Minister Gordon Brown.