Japanese police have arrested a man who pointed a knife at them near the US embassy in Tokyo as security ramps up ahead of US President Donald Trump's visit in three days' time.

A man, in his 30s, was taken into custody after pointing a kitchen knife at anti-riot police officers on the street, the Asahi newspaper reported.

During the apprehension, a male officer was injured in his right heel from the knife and was hospitalised, the report said, citing police sources. It did not make clear how the injury occurred.

The motive behind the detained man's move was not immediately known. He has not made any comments on the US or Trump so far during police interrogation, public broadcaster NHK reported.

Police set up a cordon and were investigating the site right across the US embassy in downt

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