Former education minister Simon Birmingham vetoed $4.2 million in recommended university research grants, the first time a minister has used such powers in more than a decade.

Senator Birmingham blocked federal funding for 11 projects in the humanities and the arts at leading research universities last financial year, a move Labor has dubbed as "politicisation".

The vetoed grants included nearly $1 million for a project called "Writing the Struggle for Sioux Modernity", $391,574 for "Price, Medals and Materials in the Global Exchange", $330,466 for "Legal Secularism in Australia", $336,000 for "Soviet Cinema in Hollywood Before the Blacklist, 1917-1950" and $162,000 for "Beauty and Ugliness as Persuasive Tools in Changing China’s Gender Norms".

Former education minister Simon Birmingham said taxpayers didn't want their money spent on frivolous research. Credit:Alex Ellinghausen

The secret interventions were revealed in a late-night Senate estimates hearing on Thursday. On Friday, Senator Birmingham - who is now the Minister for Trade - defended his decisions, saying he approved more than 99.7 per cent of recommended grants during his tenure.