Toronto police issued a city-wide alert for Rob Ford's SUV on Aug. 29 after witnesses called police with concerns about the Toronto mayor's fitness to drive, CBC News has learned.

The calls to police came in response to Ford's behaviour at a barbecue attended by Prime Minister Stephen Harper at Sunnybrook Park.

CBC News has learned that when Ford got behind the wheel to leave the event, his departure set off a series of calls to a police dispatcher.

On that evening, the mayor became the focus of a city-wide police alert, with patrol cars ordered to keep a lookout for his vehicle.

Ford had attended the barbecue hoping to speak with Harper about getting federal money for the Scarborough subway. That meeting never happened.

Later in the evening, police spotted Ford's vehicle in the parking lot of the Grand Hotel & Suites at 225 Jarvis St., where Ford was staying. CBC News has learned that a police sergeant spoke to Ford inside a hotel room and told the mayor that police had been looking for his vehicle and told him why.

CBC News has learned that police spoke with Ford at this hotel after the Aug. 29 barbecue. (CBC)

Ford was not charged in the incident and it appears the investigation did not proceed further.

Members of council have raised concerns recently about Ford's drinking and Ford himself admitted recently he has driven after drinking alcohol.

That statement came after Ford admitted earlier this month that he has smoked crack cocaine while serving as mayor.

That admission set off a whirlwind few weeks for Ford who was stripped of much of his powers and office budget by city council.

Court documents have revealed that for much of the summer Ford and his friend and occasional driver Alexander (Sandro) Lisi were under police surveillance. Lisi is now facing extortion and drug trafficking charges.

CBC News has learned that police surveillance teams were not watching Ford on the night of the Aug. 29 barbecue.