Turnbull promised to push for changes to 18C in bid to topple Abbott

Malcolm Turnbull reportedly told Liberal MPs he would push for controversial changes to section 18C of the Racial Discrimination Act in return for support to topple Tony Abbott as prime minister.

A number of MPs in favour of altering the legislation said Mr Turnbull assured them should he be instated as prime minister he would put 18C back on the government agenda after Mr Abbott abandoned the bid when it came up against opposition in the Senate, The Daily Telegraph reports.

"There was a deliberate impression left that he would put it back on the table," a senior Liberal source is quoted as saying.

Two MPs, who declined to be identified, said the pledge was part of Mr Turnbull's appeal for the Liberal Party leadership last September while Mr Abbott has hinted that ditching 18C was a factor in his removal from the top job. 

However, just over a month after assuming the prime ministership Mr Turnbull reportedly ruled out making any changes to 18C.

The Prime Minister's Office has declined to comment.

Section 18C makes it unlawful to "offend, insult, humiliate or intimidate" on the basis of "race, colour or national or ethnic origin".

Its critics argue it impedes free speech.

The clause has come under renewed scrutiny recently with crucial crossbenchers in the senate keen to have the legislation debated.

One of them, NSW Senator David Leyonhjelm, filed a complaint this week with the Human Rights Commission under 18C after a Fairfax journalist described him as an "angry white male".

The senator said he chose to launch the complaint to highlight the "absurdity" of the law and has previously said that people can simply chose not to be offended. 

Senator Leyonhjelm said he plans to introduce a bill to amend section 18C.