Media playback is unsupported on your device Media caption Doug Ford: "I'll continue to stand by my brother"

Embattled Toronto Mayor Rob Ford has taken a leave of absence from city hall and his campaign to seek treatment for substance abuse.

His brother Doug Ford, a city councillor, said he felt a "sense of relief" the mayor was getting help.

"He knows he has let people down," Doug Ford said.

Rob Ford, who is seeking re-election on 27 October, has been stripped of many of his powers after admitting using and purchasing illegal drugs while mayor.

'Had his chance'

Analysis This may be Rob Ford's best shot at winning another four years in office. The polls show that despite the embarrassing videos, outbursts and antics, he remains in contention with his two chief challengers, John Tory on the centre-right and Olivia Chow on the left. That is because his core supporters in Toronto's inner suburbs - the "Ford Nation" - are steadfast in their loyalty. But with months to go until October's vote, it remains to be seen whether he can build on that base among the mass of Toronto voters who are embarrassed by his behaviour or who disagree with his conservative politics. If Mr Ford emerges from his treatment looking healthy, sober and ready to get to work, he may convince Toronto to give him another chance.

Following months of denials, Rob Ford admitted last year to smoking crack cocaine in a "drunken stupor" after police said they had obtained a video that appeared to show him taking the illegal drug.

"Rob has faced his problems and decided to seek professional help," Doug Ford said on Thursday, tearing up with emotion.

"He knows he has let people down, he let his friends down, his colleagues... and the people of Toronto. I love my brother... I'll continue to stand by my brother."

Mr Ford's challengers in the upcoming election reacted swiftly to the announcement.

"On a personal level, I am relieved Mayor Ford is getting help," businessman John Tory said in a statement. "For the good of the city, I call on Mayor Ford to resign."

Former New Democratic Party MP Olivia Chow said his decision to seek treatment came too late.

"I am sure everyone in our city joins me in extending hopes for him as a person to recover from this sickness," she said.

"As a mayor, however, he had his chance. He chose to ignore calls to get help last year. The appropriate time to take a leave was then. The appropriate course now is for voters to choose a new mayor."

Media playback is unsupported on your device Media caption Toronto's controversial mayor Rob Ford says he is seeking help for substance abuse, as David Willis reports

Mr Ford was first elected to lead Canada's largest city in 2010 on a pledge to tackle wasteful spending at city hall, drawing much of his support from the suburban areas of Toronto.

He soon privatised rubbish collection across much of the city and did away with a vehicle tax. But he soon became bogged down in disputes with the council, and developed a reputation for public drunkenness.

Since the rumours of the crack cocaine video emerged last year, other videos have surfaced showing him ranting obscenely in an apparently intoxicated state.

Stripped of authority

Allegations have also surfaced in police documents that Mr Ford used racially abusive language, threatened staff, sexually propositioned a female colleague, and snorted cocaine in a restaurant. He denies these allegations.

In the latest potentially embarrassing development, the Toronto Sun said it had obtained a new audio recording of him making abusive comments about Councillor Karen Stintz, who is running for mayor, and other politicians.

Image copyright AP Image caption Toronto's mayoral candidates, from left to right: Karen Stintz, John Tory, Olivia Chow, David Soknacki and Rob Ford

In the fallout from the drugs scandal, the city council stripped Mr Ford of most of his mayoral powers and his budget, rendering him effectively mayor in name only, analysts say.

But Mr Ford has brushed aside pressure to quit, saying voters will decide whether to keep him in office in the October election.

He has said his track record spoke for itself, and recent polls have showed him running in contention with his chief challengers Mr Tory and Ms Chow.