Prime Minister Justin Trudeau on Wednesday insisted that Canada's last two elections were indeed "decided by Canadians," as he pushed back against criticism that his government had not done enough to thwart foreign interference.

Trudeau testified for hours before an independent commission probing allegations China and others sought to meddle in Canada's democratic process -- as well as Ottawa's response.

"Those elections held in their integrity, (they) were decided by Canadians," Trudeau testified about the 2019 and 2021 votes, both won by his Liberal Party.

Ministers, intelligence officials and senior Trudeau aides also testified at the hearings, which were organized to try to shed light on a political scandal that has shaken Canada for more than a year.

The opposition Conservatives have accused Ottawa of turning a blind eye to supposed interference, particularly by China. Beijing has rejected allegations of meddling.

An intelligence report submitted to the commission described China's activities as "sophisticated, pervasive, persistent and directed against all levels of government and civil society across the country."

Trudeau and several of his ministers who appeared at the inquiry however downplayed the intelligence, saying it was often not conclusive.

The prime minister pointed to an example of a foreign diplomat caught boasting to superiors that they had successfully swayed a Canadian election outcome, saying: "Bragging is not doing."

In another example, he said he was presented with insufficient evidence to overturn the nomination of a candidate accused of being in the pocket of Beijing.

During three and a half hours of testimony, Trudeau said countering foreign disinformation in elections "was not on the radar at all" when he came to power in 2015.

"So we started from a standing start," he said, outlining several checks put in place by his administration since then.

"There is always more to do," he added.

Erin O'Toole, Trudeau's main rival in the last ballot, told the inquiry he believed his Conservatives lost up to eight seats as a result of foreign meddling in the 2021 election that returned the Liberal Party to power, again with a minority government.

The Conservatives, it was argued, had taken a strong stance against China over its human rights record and security crackdown in Hong Kong and was viewed less favorably by Beijing than Trudeau's Liberals.

Trudeau rejected that assessment, telling the inquiry: "It just would seem very improbable that the Chinese government itself would have a preference in the election."