Canadian Prime Minister Justin Trudeau's brownface picture scandal deepened on Thursday as new damaging images emerged, and the Liberal leader reached out to his candidates in next month's federal election to apologise.

With less than five weeks to go before a national vote, Time magazine published a picture of Trudeau on Wednesday in brown face from a 2001 ‘Arabian Nights’ party when he was a 29-year-old teacher at a private school in Vancouver.

After apologising to Canadians in a hastily staged meeting with the media on his campaign plane on Wednesday, Trudeau held a conference call for all his 338 candidates on Thursday.

‘The prime minister expressed his apology and regret and said this happened 20 years ago,’ one Liberal on the call said. ‘He said this is the moment for us to continue to work together to understand the pain of people who are on the receiving end of racism and stereotypes.’

The Liberal leader has two campaign events planned for later on Thursday, and is due to speak to reporters at an event in Winnipeg, Manitoba, at 2:15 p.m. ET (1815 GMT).

Even before the brownface scandal, the race going into the Oct. 21 vote was tight. But the release of the bombshell images could be a turning point, in part because Liberals have traditionally attracted support from immigrant communities.

‘It is clearly very damaging at this time and the full impacts will not become clear for a week or so,’ said Frank Graves, head of EKOS Research polling company.

‘I don't think it will be fatal but time will tell. The Liberals have high ground on the diversity and racism file, and Trudeau needs to unremittingly note how he screwed up... Voters will then decide,’ he said.

Trudeau has championed racial equality and diversity as prime minister over the past four years, and he has three prominent ministers of Indian descent in his cabinet.

Greg Fergus, a black Liberal legislator from Quebec, said Trudeau had called him before the story broke to apologize.

‘I don't believe that anybody has ever lived their lives without making errors,’ Fergus told reporters in Ottawa, saying Canadians should focus on ‘all the amazing things we have done for diversity’.

‘DAY O’

On Wednesday, Trudeau also admitted to performing ‘Day O’, a traditional Jamaican song made famous by Harry Belafonte, in brown face during a high school talent show years earlier. The Canadian Broadcasting Corp then published a picture from the performance that a Liberal spokeswoman confirmed as authentic.

Global News put out a video showing Trudeau again in dark make-up making faces and sticking his tongue out. It was not immediately clear exactly when that video was from.

‘We can confirm that it is him and it's from the early 1990s,’ a Liberal official said.

Conservative Party leader Andrew Scheer, Trudeau's main rival, said that the video was proof that the prime minister had lied during his apology on Wednesday because he only mentioned having dressed in brown face twice.

‘He did something that was racist and he lied about the extent of such activities,’ Scheer told reporters in Saint-Hyacinthe, Quebec.

But Scheer also acknowledged the Conservatives had leaked the video to Global News.

Trudeau has seen his once sky-high popularity hurt by a series of missteps, including a ruling last month by a top watchdog that he had breached ethics rules by pressuring the former justice minister to ensure a major construction firm avoid a corruption trial.

On Wednesday, Trudeau brushed off suggestions he might quit.