Taiwan's coast guard chief said Monday an average of six to seven Chinese vessels have been in waters around Kinmen island every day since a fatal boat incident last month.

A Chinese speedboat carrying four people capsized on February 14 near Kinmen while being pursued by the Taiwanese coast guard, throwing all on board into the water.

Two of the crew died and two others were rescued and temporarily detained in Kinmen -- a territory administered by Taipei but located just five kilometres (three miles) from China's city of Xiamen.

The incident has fuelled tensions between China and Taiwan, a self-ruled island that Beijing claims as part of its territory.

"Since the February 14 incident, they deliberately have six to seven vessels on average daily and as many as 11 vessels during the daytime," Taiwanese coast guard chief Chou Mei-wu told a parliamentary committee, referring to China.

"They are not only coast guard boats, but also maritime surveillance ships and other vessels from (Chinese) authorities. Their intention is to surround Kinmen," he said.

Chou said the coast guard had "expelled" the vessels, but he did not provide details.

A survivor of the boat crash has reportedly claimed the vessel was "rammed", while the Taiwanese coast guard has said it "lost its balance and capsized".

Beijing has never renounced the use of force to bring Taiwan under its control, and in recent years has ramped up its rhetoric of "unification".

It has stepped up military pressure on Taiwan by deploying warplanes and naval vessels around the island on a near-daily basis.