Transport authorities in New Delhi on Monday announced a ban on Uber services in the Indian capital, saying their investigation revealed the company was violating permit rules.

Authorities say Uber was operating as a local taxi on a national permit. Commercial vehicles on national permit cannot operate as taxis ferrying passengers from one destination to another within a city.

New Delhi police say they will implement the ban. But Uber said it hadn't been officially notified of the measure and that its service was still operating in the city.

Singh said police were exploring what he called Uber's "possible legal liability" in the rape case, in which a 26-year-old woman alleges she was assaulted at the weekend after being taken to a deserted stretch of road in an Uber car she had ordered.

New Delhi police have filed a case against Uber "under sections relating to cheating and violation of government rules and orders," said Deputy Police Commissioner Madhur Verma.

Shiv Kumar Yadav, the Uber driver accused of raping his passenger, remains in police custody for questioning.

Police say Yadav's address and background weren't verified in his driver registration.

Uber said in a statement that it "exclusively partners" with registered drivers who have been through the commercial licensing process and who have government identification and state-issued permits.

It called the alleged rape "abhorrent" and said it was cooperating with the investigation.

Uber drew heavy criticism last month after one of its executives suggested that it would be fair game to dig up dirt on journalists who were critical of his company.

A U.S. tech journalist singled out by the executive said there was an"escalating and scary pattern of misogyny" at Uber, citing the way Uber has dealt with assault complaints from female riders and a recent promo offering free rides with beautiful women.

CNN's Harmeet Shah Singh reported from New Delhi, and Jethro Mullen wrote from Hong Kong.