One Nation's Pauline Hanson tells court she did not know Greens ...

One Nation Leader Pauline Hanson has told a Sydney court she didn’t know that a fellow senator was Muslim when she told her to “piss off back to Pakistan” on social media.

Greens deputy leader Mehreen Faruqi has taken Senator Hanson to the Federal Court over a tweet posted on the day Queen Elizabeth II died in September 2022.

Senator Faruqi had called for a treaty with First Nations and said she couldn't mourn "the leader of a racist empire built on stolen lives, land and wealth of colonised people".

Senator Hanson responded with a post that said, in part, that it was clear Senator Faruqi was "not happy" and should "pack your bags and piss off back to Pakistan".

The deputy Greens leader claims that constituted racial discrimination, but Senator Hanson's lawyers say Senator Faruqi's tweet was intended to provoke a response.

Senator Hanson was today cross-examined by Senator Faruqi's counsel, Saul Holt KC, who accused her of lying under oath by denying that she knew Senator Faruqi was Muslim at the time of the tweet.

"I've never gone and asked. I don't ask anyone their religion," Senator Hanson said.

Senator Hanson said she also wasn't aware that 97 per cent of the Pakistani population are Muslim.

Mr Holt pressed the politician about the contents of an affidavit sworn in January.

"If it is true that you didn't know that she was a Muslim, why on earth would you not have said that in the affidavit?" he asked.

"It never crossed my mind," the senator replied.

Mr Holt later said: "You have lied on oath in this court in your claim that you did not know that Senator Faruqi was a Muslim, Senator Hanson, haven't you?"

"When I put the tweet out, I didn't know," she insisted.

Senator Hanson said today that, when she sent her tweet out regarding Senator Faruqi, she did not know the Greens senator was Muslim.(AAP: Dan Himbrechts)

Mr Holt played a range of videos in which Senator Hanson expressed her views about migration, including a 2010 interview during which she said she wouldn't sell her house to a Muslim and a 2017 press conference in which she described Islam as a "disease".

Senator Hanson denied that she believed that Senator Faruqi, as a Muslim, should never have been allowed to migrate to Australia — because "she's not an extremist" and had obtained Australian citizenship.

"Quite apart from the tweet that she put out on the day that the Queen passed … you already wanted her to piss off back to Pakistan," Mr Holt said.

Senator Hanson replied: "Disagree".

Later, Senator Hanson was asked whether she had ever suggested a migrant from a white background should leave Australia.

"I probably have," she replied.

The senator said she was "distraught and very upset" on the day of the Queen's death.

She said Senator Faruqi's tweet, brought to her attention by a staff member, was insulting.

Earlier, a Deakin University academic in race relations, Yin Paradies, was cross-examined by Sue Chrysanthou SC, representing Senator Hanson, about his report on the likely impact of the tweet.

He disagreed that he had "no basis" to conclude the tweet would likely have a negative impact on readers who shared any or some of a list of group attributes, including migrants or those with migrant heritage born in Australia.

"Given the literature and evidence to date, that form of racism applied to people who have at least one of those group attributes is likely to have a negative impact on somebody vicariously," Professor Paradies said.

"It's a fairly strong form of racism. It's very exclusionary and very much about who belongs and who doesn't belong, certain parts of the tweet."

Ms Chrysanthou questioned the academic on his own online activity by reading out tweets he published on Australia Day in 2022 and 2023 about colonisation.

Professor Paradies disagreed that the views he held affected his approach to answering questions about Senator Hanson's conduct.

The hearing continues tomorrow.