Half of the most senior staff in the government's public spending watchdog are not professionally qualified to do the job, it has been revealed.

The Comptroller and Auditor General's (C&AG) office, which last week produced scathing reports into the wasting of taxpayers' money in Fás and the wider public service, has been severely criticised in a peer review conducted by international auditors.

The review said: "In an office which has set its sights on being fully professional it seems to us unacceptable that a large proportion of the managing and directing grades on financial audit are not qualified. Our understanding is that of the order of six of the 12 deputy directors and 20 of the 40 senior auditors are not professionally qualified".

The office, which is headed by John Buckley, is part of the civil service and legally cannot insist that applicants for jobs have professional qualifications.

A spokeswoman for the C&AG said that it ensures that only qualified staff work on audits while its unqualified staff compile reports. In addition, five of the 12 deputy directors in the office have opted for early retirement and will not be replaced, meaning that more experienced and qualified staff will be lost.

Meanwhile the Sunday Tribune can reveal that a report into the controversial Fás Science Challenge Programme found that students who participated in the programme, on which over €6m was spent, would have fared just as well if they hadn't attended it.

The report, ordered by Tánaiste Mary Coughlan, also said that it was outside the organisation's main remit and was spending inexplicably large sums of money on advertising and overseas travel.

It recommended that the programme be wound down as soon as possible to ensure no further money was wasted.

A figure of €6.645m was spent on sending students to Florida to participate in the internships with scientists in Nasa.

Of the money spent since the programme's inception in 2003, 26.5% of it – or €1.76m – had gone on accommodation and flights.

The vast majority of that related to flights to Florida for Fás bosses, who routinely travelled first class or business class and stayed in upscale hotels.

In 2005, a total of €149,544 was spent on transatlantic flights, rising to €210,345 the following year.

During the same period, accommodation – principally hotels – cost €266,803 in 2005 and €278,405 in 2006. In 2007, the cost of accommodation reached an incredible €528,117.

A further €3.2m was spent on "advertising, publicity [and] events" to publicise the project, according to the report.

Just 243 students had actually participated in the programme, meaning the cost "per unit" ended up at a massive €27,349.

Recommendations from the investigation said the programme should be "discontinued" once all students had completed their courses.