US President Donald Trump called for calm about the protests in Hong Kong, which in recent days have heated up again with strikes and occupations of government buildings, police stations, subway stations and the airport.

"Our Intelligence has informed us that the Chinese Government is moving troops to the Border with Hong Kong. Everyone should be calm and safe!" Trump said on his Twitter account.

The protests in Hong Kong began last March against a push by local authorities to enact an extradition law, which, according to its opponents, would make political dissidents and sectors critical of the Communist regime liable to be sent off to China and put on trial without any legal guarantees.

Before calling for calm, Trump spoke ironically about the supposed implication of the United States in the demonstrations.

"Many are blaming me, and the United States, for the problems going on in Hong Kong. I can't imagine why?" the president tweeted.

In a statement to reporters in Morristown, New Jersey, Trump described the situation in Hong Kong as "very tough."

"The Hong Kong thing is a very tough situation, very tough. We'll what see what happens. But I'm sure it'll work out. I hope it works out for everybody, including China, by the way," he said.

By last June the protests had mobilized hundreds of thousands of people and have been marred by episodes of violence, strikes and attempts by activists to affect the normal life of the city with strikes and occupations of government buildings, police stations, subway stations and the airport.

Hong Kong is in practice independent of China in judicial matters, with relations between the two countries maintained under the official principle of "One Country, Two Systems," with Beijing allowing the former colony wide autonomy in all fields except foreign affairs and defense.

The current tensions, the worst the former British colony has suffered since the 1997 return of Chinese sovereignty - but with considerable autonomy - have led a number of countries to advise their citizens against traveling to Hong Kong, while the fear grows of an invasion by the Chinese army and armed police. EFE-EPA asl/cd