Taiwan's coast guard has arrested a Chinese man who sailed a small boat into a harbor at the mouth of a river leading to Taipei.

Coast guard officials say they spotted a suspicious vessel about 10 kilometers off the coast of Tamsui in northern Taiwan before noon on Sunday.

The boat later entered the river and collided with other vessels at a ferry terminal. The man was arrested on the spot.

Some Taiwanese media reported that he sailed from Fujian Province in southern China.

Investigative authorities are questioning the man about the reason for the intrusion.

The boat entered a river running through residential districts in northern Taiwan, only 20 kilometers away from central Taipei where the presidential office is located.

The river mouth is regarded as a key area in terms of security.