Uber, the ride-hailing app giant, clashed with drivers from Lyft and the city's cab companies Tuesday over access to the Democratic National Convention's venue.

Cab and Lyft drivers accused Uber of making it difficult to drop off passengers near the Wells Fargo Center, where convention events are held. Uber has an agreement with the Democratic National Committee that granted it an exclusive Uber lounge, where passengers can wait to be picked up, and gave it rights to dispatch car service for convention VIPs, organizers said.

The head of the cab drivers' union said Uber workers had tried to keep drivers away from a main access spot for the Wells Fargo Center near 10th Street and Packer Avenue on Monday night as the convention opened.

"There's only one entrance," Ron Blount said. "How can it just be exclusively theirs?"

Uber said its staff had only diverted vehicles from an area assigned exclusively to the company for dropping off or picking up passengers.

"Due to a logistical issue yesterday, there were cases in which non-Uber rides attempted to drop off at the DNCC-assigned Uber lot," Craig Ewer, an Uber spokesman, said Tuesday.

The ride-hailing app company Lyft shared the cabdrivers' concerns.

"We did get reports of drivers who were turned away at the perimeter by someone wearing an Uber shirt," said Lyft spokeswoman Chelsea Wilson. "It's unfortunate that anyone would try to make it harder for drivers to do their jobs and for passengers to get around."

The walk from the Wells Fargo Center to the Uber tent in Lot T outside Citizens Bank Park takes about 10 minutes.

Around 7 p.m. Tuesday, as delegates trickled in before prime-time speeches started, there was ample room in the Uber lounge, an air-conditioned tent with a seating area, charging stations, water bottles, Kind protein bars, coffee, and M&Ms bearing the Uber logo.

Most car services were allowed to drop off passengers at the Wells Fargo Center at Lot V, while Ubers were assigned to Lot T, DNC spokesman Lee Whack said, adding that all legal car services had access.

"Any and every legal transportation service has access to the parking lots of Wells Fargo Center to pick up and discharge passengers," he said.

Blount also said he saw Uber vehicles parked at cab stands throughout the city in the first two days of the convention.

Shortly before the convention, Uber and the Philadelphia Parking Authority reached an agreement that allowed the service, which was technically illegal in the city, to operate freely. That agreement was bolstered when the Pennsylvania legislature passed a bill two weeks ago giving ride hailing app companies legal status in the city until the fall. That frustrated cabdrivers, who have lost significant business since Uber came to Philadelphia. They demonstrated Monday night outside an Uber-hosted party to fight for guaranteed minimum wages for drivers.

The convention has been a boon to both Uber and Lyft, the companies said. Lyft reported boosted business and Uber reported 60 percent more customers this Monday than the previous week.

As the convention continued, Uber officials said they expected fewer disruptions.

"The appropriate arrival lots have since been clarified, and we expect the process to run smoothly tonight," Ewer said.

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Staff writer Julia Terruso contributed to this article.