Transport for London has seen cases of internal fraud more than double from 60 to 123 investigations this year with four investigations centered on the alleged payment of thousands of pounds to deceased pensioners.

A report being presented to its internal audit committee revealed a series of financial irregularities at TfL, which is responsible for the capital's tube and bus services, main roads and the congestion charge.

A spokesman said that there were '68% more investigations' this year than in 2004 but said this was caused by the company becoming 'much more integrated' as well as becoming 'one team'. He added the greater integration would lead TfL to be in a 'better position' to crack down on fraud and that 123 investigations out of 19,000 employees was 'small'.

The four cases of payments made to deceased pensioners were uncovered when inspectors checked their details against a list of active National Insurance numbers.

The TfL spokesman refused to reveal the amount involved, but added that a family member in one case had been found guilty of fraud earlier today. TfL is running a five-year £10bn investment programme, including the £1bn East London line extension and the proposed extension of the congestion charge zone.