Controversial Mayor of Toronto Rob Ford is to return to work on Monday more popular than ever after a stint in rehab for his internationally publicised alcohol and drug abuse.

Mr Ford, 45, has moved into second or third place in the lead-up to municipal elections in October, according to the latest polls, despite being absent from the campaign trail for a month to attend a rehab centre.

His surprise rebound in popularity comes after support plunged to a low of 32% at the beginning of June when he disappeared from the limelight.

"With his return now imminent, interest in the mayor is beginning to grow, and with it, as usually happens, his approval," said Lorne Bozinoff of Forum Research, which published a poll showing Mr Ford behind frontrunner Olivia Chow by seven percentage points.

"We'll see if this is a temporary phenomenon, or a sustained surge which will carry him back into the campaign he left so abruptly," added Mr Bozinoff.

Days prior to Mr Ford's highly anticipated return, Toronto City Hall was eerily quiet with most councillors and staff away on vacation.

Mr Ford took a leave of absence from City Hall in May in the middle of his re-election campaign to enter rehab after several videos surfaced over the past year showing him apparently smoking crack cocaine.

The latest video reportedly showed him smoking the addictive drug with his sister in her basement in April, refuting Mr Ford's claims that he had kicked the habit.

The mayor's drug abuse was first revealed last year when an alleged drug dealer tried to sell another video of him smoking crack to the media.

At first, Mr Ford denied using the hard drug but later acknowledged he had smoked the crack while in a "drunken stupor," and yet insisted he was not an addict.

Since then, Mr Ford has been filmed numerous times in public behaving erratically.

Toronto City Council stripped him of most of his mayoral powers in November over his misconduct.

In rehab, the mayor reportedly underwent almost 500 hours of therapy, including group and one-on-one help.

Upon his return, Mr Ford is likely to continue campaigning on a give-me-another-chance platform.

He is expected to address the media and has invited city councillors to have an "informal meeting" to discuss "issues facing Toronto and how we can work together to move forward in a constructive and collaborative way," according to an email to councillors published by the daily Globe and Mail.