Britain's government says China has closed what were alleged to be police stations at four locations across the country.

The government on Tuesday announced the results of its investigation of the sites, including the one in London.

Last year, an NGO based in Spain reported there were more than 100 Chinese overseas police service centers in over 50 countries, including Japan, the United States and some in Europe, to monitor Chinese dissidents and exert pressure on them.

British security minister Tom Tugendhat quoted the Chinese Embassy as saying all such stations had closed permanently. He said no evidence of illegal activity on behalf of the Chinese state has to date been found at the sites.

Tugendhat said the presence of unofficial Chinese police service stations "will have worried and intimidated" those who left China to seek safety and freedom in the UK and is unacceptable.

Chinese Foreign Ministry spokesperson Wang Wenbin told reporters on Wednesday that such posts do not exist. He said China "strictly abides by international law and respects other countries' judicial sovereignty."

Wang said Britain should "respect the facts" and "stop hyping up the matter and smearing China."

Other countries are also investigating similar sites.

In April this year, the US Department of Justice arrested two men for allegedly establishing and operating a secret police station in New York.