Theresa May is a leader on borrowed time: Lord Patten

U.K. Prime Minister Theresa May is living on borrowed time, according to the former governor of Hong Kong.

On Monday, Theresa May's Conservative Party signed a deal with Northern Ireland's Democratic Unionist Party (DUP).

The deal promised the ruling minority Conservative government the support of the 10 DUP politicians in upcoming votes. In exchange, the Conservative's dropped several election pledges and promised £1 billion ($1.3 billion) of new funding for Northern Ireland, to be spent over the next two years.

British Prime Minister and Conservative Party leader Theresa May speaks at the declaration at the election count at the Magnet Leisure Centre on June 9, 2017 in Maidenhead, England.
Getty Images

Chris Patten, former governor of Hong Kong and member of the U.K. House of Lords for the Conservative Party, criticised the deal with the DUP, calling it "very mistaken".

"You give people a bung, which is what it is, in order to support you and sooner or later they come back for more bungs," he told CNBC's Street Signs.

"The idea that this is the last time the DUP will ask for loot is crazy. Of course Northern Ireland wants more spending, and so does Scotland, Wales and large parts of England."

He added that the deal would harm the Conservative's public image, and could endanger future cross-party talks. He also went on to discuss the future prospects for Theresa May.

"I think she'll last as long as her colleagues think that it would be dangerous for her not to last. I think she's on borrowed time, but nobody knows how much has been borrowed."

UK Conservative/DUP deal 'very mistaken': Chris Patten
UK Conservative/DUP deal 'very mistaken': Chris Patten

The deal was made two weeks after the U.K. general election, which was held on June 8. Theresa May's party failed to increase its majority in the U.K. Parliament, going on to lose 13 seats. Theresa May was heavily blamed for the election result; the U.K.'s former finance minister, now newspaper editor, George Osborne, called the prime minister a "dead woman walking", during a televised interview.

Patten was on CNBC to discuss the 20th anniversary of the handover of Hong Kong from the U.K. to China. He criticized how some countries and businesses treat China.

"I've never been against helping China to develop as a modern economy, as part of a global economy," he said.

"What I'm not in favour of is this kowtowing to China and thinking that's the only way you can do trade or business with them. I don't think it's true for one moment."

Follow CNBC International on Twitter and Facebook.