As police continue to crack down on illegally parked vehicles in Toronto, some courier drivers say the "Tag and Tow" campaign is putting them in a tight spot: deliver a package on time or get a ticket.

In January, Mayor John Tory rolled out his zero-tolerance policy for illegally parked vehicles during rush hour. Vehicles that are parked along major roads during morning and afternoon rush hours are now towed at the owner's expense. Drivers may be charged up to $230 to get their vehicles back, and delivery trucks drivers up to $1,000.

The city has since expanded the campaign.

Out-of-province vehicles with three or more outstanding Toronto tickets are now immediately towed. Vehicles with three or more tickets that are parked illegally outside of rush hour will also be towed.

According to ICS Courier driver David White – whose delivery van is the city's worst parking offender with 612 outstanding tickets – the policy means his customers may not get their packages on time.

"It's so sad to know that I'm trying to make you guys get your package on time," he told CTV Toronto on Thursday. "It does affect business because I've got to park all the way down the street and walk it up."

White's ICS van previously had an Alberta licence plate, but it now has a local one. He isn't the only driver who says the parking blitz is potentially affecting his customers.

"At the end of the day, I could drive around the city trying to find parking and then I don't get my job done," Van Houtte driver Joshua Earlls said.

But despite the inconvenience to drivers, police say the parking campaign is helping to reduce traffic congestion.

"It seems to be working – traffic flow is better," said Philip Heim of the Toronto Police Service's parking enforcement unit.

This week, police have towed more than 88 out-of-province vehicles so far.

Police say they are on the lookout for vehicles on their repeat offenders list. There are approximately 7,700 of them in the city that have been issued a total of 150,000 parking tickets a year.

Heim said although he understands the frustration some delivery drivers face because of the "Tag and Tow" campaign, his priority is to make "sure traffic flow is moving in this city and people are getting where they need to be."

ICS previously told CTV Toronto in a statement that it is "committed to serving Torontonians in a timely and secure manner without adding to the city’s traffic congestion."

With a report from CTV Toronto's Natalie Johnson