• Glasgow's underground, which is controlled by SPT
An external audit carried out by KPMG found that management "shredded"
expense receipts and that 32,000 in claims was unaccounted for.
The probe also concluded that a three-day trip to Manchester in 2008 had been organised to coincide with Rangers' Uefa Cup final appearance.
Close to 40,000 was spent on trips to New York, India and Dubai.
Four directors of the transport body have left in the aftermath of the row, including former chairman Alistair Watson and chief executive Ron Culley, who both quit on health grounds.
Davie McLachlan stepped down as vice-chairman and former director of communications Bob Wylie left during restructuring.
Today's report found that between April 2007 and March 2009, around 32,000 of the 57,556 spent on SPT's credit card was not supported by receipts.
"We were advised by management that the receipts and other supporting documentation were shredded by the individual responsible for the administration of corporate credit cards between the date of the internal audit and when they left the organisation," the report said.
A previous internal audit found that the credit card was used in line with established policy.
Auditors criticised a 2008 trip to a transport conference in New York by Mr Culley, Mr Watson and Mr McLachlan, which cost 17,500, including more than 100 a day on meals for the seven-day trip.
"We question the value received by SPT from this expenditure," the report said.
"We also question whether it was necessary for two members to be in attendance on this trip."
The expenses claimed include 621 spent in the Russian Tea Room, a restaurant in the city, which was attended by five people.
A trip to India and Dubai involving all three men, and a fourth SPT officer, cost 18,506, the report showed.
The role of Mr Watson and Mr McLachlan is questioned on both trips with items identified which suggest "personal expenditure and/or excessive" costs incurred.
Mr Wylie initiated a meeting with the Greater Manchester Passenger Transport Executive on May 14, the same day as Rangers' Uefa Cup final match with Zenit St Petersburg in the city, which Mr Wylie attended.
The meeting itself lasted one-and-a-half hours, the report said, but 1,495 was claimed in expenses for the three-day trip, attended by Mr Wylie and Mr McLachlan. This included the costs of taxis between Manchester and the Chester hotel where they stayed. There was also 388 spent on drinks and food.
"Personal and excessive expenditure has been incurred on this trip and should be repaid," the report said.
"The evidence suggests that this trip was arranged to coincide with the Uefa Cup final, although this is disputed by the former director of communications."
The report said Mr Wylie repaid "an amount" of expenses.
But it added: "It could be argued that the entire expenses associated with this trip should be repaid."
Today's report covers complaints made about SPT in nine areas but issues like "out-of-pocket" expenses, the use of consultants, marketing expenditure and the use of an external conference venue was found to be in line with normal procedures.
The report will be considered by SPT's audit and standards committee tomorrow.