HONG KONG (Reuters) - Hong Kong's finance chief said on Sunday the government will closely watch the impact of Britain's vote to leave the European Union on the city, which is set to affect the global economy and the territory's trade and financial markets.

"It was a big surprise when I learned the outcome of the vote," Financial Secretary John Tsang said on his blog on Sunday. "The government will keep a close eye on the development."

Tsang said Britain and the European Union will start a lengthy negotiation regarding the arrangement, and that will bring "long term uncertainty" to both the British and EU economies as well as the global and Hong Kong economies.

Tsang had said on Friday the city has enough foreign exchange liquidity to deal with a range of outcomes from the British referendum on whether to leave the European Union.

In a newspaper interview on Sunday, Hong Kong Chief Executive Leung Chun-ying had expressed confidence the city can seize advantages and deal with any challenge arising from the Brexit.

On Friday, the Hong Kong Monetary Authority asked banks to maintain ample cash conditions with them.

(Reporting by Donny Kwok; Editing by Sam Holmes)