Where in the world is Rob Ford?

Questions arose about the whereabouts of Toronto's crack-smoking mayor Tuesday after it was reported that US border agents have thwarted his efforts to enter a rehab program in Chicago.

Mayor Rob Ford, 44, apparently flew to the "Windy City" on May 1 aboard a private jet and was expected to check in at a rehab center for drug and alcohol abuse.

He took a leave of absence from city hall in the middle of his re-election campaign and made the trip after another video surfaced showing him apparently smoking crack recently.

But Canadian media said Ford turned back after landing in the US city, and officials are not saying where he ended up.

The Globe and Mail newspaper said he decided not to seek entry into the United States after a brief chat with US customs agents.

Ford "was not denied entry, per se," the paper quoted Roy Norton, the consul general of Canada in Chicago, as saying.

Rather, "he voluntarily withdrew his application to enter the USA."

Ford's brother Doug meanwhile told reporters in Toronto that the mayor has entered a rehab program.

"Due to confidentiality to not only the mayor but to the people in the rehab program, I'm not at liberty to say. He's in a rehab facility, 100 percent, and he's getting the support that he needs," Doug Ford said at Toronto city hall.

"He's doing great. Everybody's concerned that he's in rehab. He's in rehab, he's doing good, that's all that matters," he said.

Ford burst into international headlines last year when an alleged drug dealer tried to sell a video of the mayor allegedly smoking crack to media outlets in Canada and the United States.

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

Since then Ford has been filmed numerous times in public behaving erratically. The latest video showing him allegedly smoking crack was filmed less than two weeks ago in the early hours of April 26.