The Greens have cited the rightwing terrorist attack in Christchurch to renew calls for a parliamentary code of conduct to stamp out hate speech, a push also backed by Australia’s peak Muslim body.

Richard Di Natale has written to Scott Morrison and Bill Shorten warning that the extreme rightwing nationalist senator Fraser Anning – who blamed the attack on Muslim immigration – “is not a lone voice in our parliament” and more needs to be done to prevent “hateful rhetoric”.

The call follows the Coalition and Labor reaching agreement to pass a motion condemning Anning for his “inflammatory and divisive comments seeking to attribute blame to victims of a horrific crime and to vilify people on the basis of religion”.

The Greens’ proposed code requires parliamentarians to “reject discriminatory or exclusionary statements” and guarantee they will not “knowingly humiliate or degrade an individual or community based on their colour, national or ethnic origin, culture, religious belief, gender or sexual orientation”.

In his letter Di Natale notes that both major party leaders have “condemned the abhorrent hate speech of Senator Anning” but warns that “too often, fellow MPs have fostered division when they should have been seeking to bring our nation together”.

“Too often, there have been those who have used their position of power and privilege in our parliament to attack migrants, refugees, minority communities, women and our LGBTIQ community,” he said.

“Friday’s attack makes it painfully clear that we must no longer allow hateful and divisive rhetoric to find a home in our nation’s parliament.”

The Greens attempted to introduce a code of conduct in November in the Senate, but the Liberals pushed the issue to the procedures committee, which is due to report in April. Explaining the opposition’s support for the move, the Labor senator Anthony Chisholm cited existing standing orders which ban “objectionable words”.

In her first Senate speech in September 2016, the One Nation leader Pauline Hanson called for a suspension of immigration and warned Australia was “in danger of being swamped by Muslims”.

Outrage at the speech led to Labor proposals to combine with the government to pass a new code of race ethics, which echoes an initiative advanced by the ALP and the Australian Democrats when Hanson was last in the federal parliament.

Liberal National party backbencher George Christensen rubbished the proposal as a form of “politically correct social engineering”.

The Australian Federation of Islamic Councils president, Rateb Jneid, has written to the Senate president, Scott Ryan, highlighting Anning’s “repulsive” and “outrageous” comments after the Christchurch attack.

“Senator Anning, and his words of yesterday, bring shame to your House, the whole Parliament and must call in to question his fitness to be a member,” Jneid wrote.

“On behalf of the Muslim community of this country we demand that the Senator be censured to the full extent allowable under the rules of the House and some formal code of conduct introduced to avert such despicable behaviour in the future.”

In addition to the censure motion – negotiated and agreed by the Coalition and Labor – Scott Morrison has suggested Anning should face the “full force of the law” after he punched a 17-year-old boy who egged him at an event in Melbourne.

A Change.org petition calling for Anning to be removed from the Senate has reached 869,000 signatures, the largest in the organisation’s history in Australia, according to its executive director, Sally Rugg.

However, as the constitutional law academic Anne Twomey has written in the Conversation, the Parliamentary Privileges Act currently does not allow a house of parliament to expel one of its members.

Although Anning and Hanson have been the biggest lightning rods for race-based controversy in the 45th parliament, in November 2016 the Victorian Liberal backbencher Russell Broadbent took aim at some colleagues – including Christensen for “cuddling up to Hansonite rhetoric”.

The Coalition has a patchy record on confronting white nationalism, after government senators voted for a motion that it is “OK to be white” in October only to later claim this was an “administrative error”.

Morrison himself as shadow immigration minister reportedly told shadow cabinet in 2011 the Coalition should do more to capitalise on concerns about Muslim immigration, comments which he now denies.

In August the outgoing racial discrimination commissioner Tim Soutphommasane warned that “race politics is back” and criticised Turnbull government ministers for their rhetoric on African gangs and ethnic separatism.

Soutphommasane cited the home affairs minister Peter Dutton’s calls for “special attention” for white South African farmers, then citizenship minister Alan Tudge’s claim that Australia is veering towards a “European separatist multicultural model”, Dutton’s suggestion Melburnians are afraid to go out to dinner due to African youth crime, and Turnbull’s claim there is “real concern about Sudanese gangs” in Melbourne.

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