Connex has been rapped by rail watchdogs for falling punctuality after new figures showed that more of its trains ran late.

A total of 85.9 per cent of peak-time trains run by Connex South Central between April 30 and July 22 this year were on time compared with 92.6 per cent in the same period last year.

Punctuality on off-peak services also fell from 91.7 per cent to 86.8 per cent, according to figures released by the Shadow Strategic Rail Authority.

Peak services run by Thameslink rose in punctuality from 85.3 per cent in 1999 to 86.1 per cent this year.

Connex is bidding against Govia, which runs Thameslink, for a franchise to run South Central services.

The authority is expected to decide in the next few weeks which firm has been successful.

Mike Grant, the authority's chief executive, said: "These results are not satisfactory.

Some can be attributed to events outside the control of the train operating companies, but operators need to pay attention to the immediate problems under their control.

"Their performance will influence the decision on franchise replacement."

A Connex spokesman said a shortage of drivers and poor rail infrastructure had led to the drop, but added that 250 people were now undergoing driver training to improve services.

He said the introduction of new Class 375 carriages and the phasing out of Sixties slamdoor stock by the end of 2002 would also improve punctuality.

He added: "Connex is working hard to reduce delays caused by train unreliability and is working in partnership with Railtrack to improve infrastructure reliability.

"Connex SouthCentral metro service levels are still reduced because of driver shortages and consequent overcrowding in some areas is impacting on punctuality."

Martin Walter ,of Thameslink, said: "Things are improving slowly on Thameslink but we have the problem of tracks between Brighton and London being absolutely full."