Taiwan's coast guard said on Thursday a Chinese boat that capsized during a chase was trying to evade a patrol vessel and "lost its balance" in a deadly incident condemned by Beijing.
It gave more details about the incident after China accused Taiwanese authorities of "seeking to evade their responsibilities and hide the truth" about the incident last week in which two Chinese nationals died.
The speedboat carrying four people capsized on February 14 near Taiwan's Kinmen islands while being pursued by the Taiwanese coast guard, throwing all onboard into the water.
Two other crew were rescued and temporarily detained in Kinmen — a territory administered by Taipei but located just five kilometres (three miles) from the Chinese city of Xiamen.
The incident occurred against a backdrop of heightened tensions between China and Taiwan, a self-ruled island that Beijing claims as part of its territory.
A survivor has reportedly claimed the boat was "rammed", while Taiwan insists the coast guard was following legitimate procedures.
Coast guard authorities told a news conference in Kinmen on Thursday that the Chinese boat had "lost its balance and capsized" after it was "snaking" to avoid inspection.
"During the chase, which lasted around one minute or more... the mainland boat kept snaking to get away from our patrol vessel," coast guard official Chen Chien-wen told reporters.
"The boat turned sharply to the right, causing its stern to hit the right front of our patrol vessel... The Chinese speedboat lost its balance and capsized due to centrifugal force."
Taiwan also urged China to give it time to investigate after the Taiwan Affairs Office in Beijing condemned Taipei's "rough treatment of mainland fishermen" and its "malicious action of ignoring life".
"Everyone should wait patiently for the results of the investigation by our judicial system... we just need to give it some time to collect evidence and make judgement fairly," said Jan Jyh-horng, a spokesman for the Mainland Affairs Council, Taiwan's top China policy-making body.
He told reporters "we hope they (China) can respect our judicial system".
Taiwan has defended its actions by saying the Chinese boat was in prohibited waters, while China vowed to increase "law enforcement patrol operations" in the area.
Chinese coast guard officials briefly boarded a Taiwanese tourist ship on Monday.