TAIPEI (AFP) - Taiwan on Sunday repeated calls for a joint investigation into the killing of a Taiwanese fisherman by Philippine coastguards, an incident which has ignited a major diplomatic dispute.

A team of Taiwanese investigators returned to the island on Saturday, accusing the Philippine government of failing to honour its agreement to conduct a joint probe.

"The decision to send the investigators to Manila came only after the Philippine government had agreed to let us to do so," deputy justice minister Chen Ming-tang told reporters.

He said Manila's de facto ambassador Antonio Basilio had agreed to such a move in Taipei on Wednesday, but that the Philippines had now wavered on the proposal.

Mr Chen said a joint inquiry was the only way to establish the truth about the May 9 fatal shooting of Mr Hung Shih-cheng, a 65-year-old crewman on the fishing boat.

"While our investigators can provide them with evidence they have collected, Filipino investigators can come to Taiwan to gather evidence, including talking to the other witnesses on board the fishing boat at the time of the shooting," the deputy minister said.

The coastguard has said the fishing vessel had intruded into Philippine waters and tried to ram their own patrol boat.

Mr Chen denied any intrusion, citing a voyage data recorder on the fishing boat.

Taiwan has rejected Manila's apology and slapped sanctions on the Philippines, including a ban on the hiring of new workers, recalling its own envoy and staging a drill in waters off the northern Philippines.

It is angry at Manila's description of the death as "unintended". Taiwan's President Ma Ying-jeou has termed the killing "cold-blooded murder", referring to more than 50 bullet holes in the fishing boat.

Mr Amadeo Perez, a personal envoy from Philippine President Benigno Aquino was forced to return home on Thursday after Taipei rejected the apology he conveyed from the president.

Taipei has repeatedly pressed Manila to issue a formal government apology, to compensate the fisherman's family and to apprehend the killer.

In Manila, Mr Perez said his country is waiting for tempers in Taiwan to cool before settling the dispute.

Issues like Manila's "one-China" policy and comments by Taiwanese investigators branding the incident as murder have complicated the situation, said Mr Perez, chairman of the Manila Economic and Cultural Office.

"We are waiting for the right time because I was told by the secretary-general for Asian affairs, we should wait for the temperature in Taiwan to cool," Mr Perez said in an interview with DZMM radio.

"The Taiwanese are highly emotional and... the media in Taiwan is heating things up so tempers are running high."

Mr Perez, whose office is in charge of relations in the absence of diplomatic ties, said the Philippine Justice Department was still studying a request for a joint investigation when the Taiwanese made their allegations this weekend.

Mr Perez also said that Taiwan wanted President Aquino personally to write a letter of apology, but this could be considered a violation of Manila's one-China policy - which recognises Beijing rather than Taipei as the government of China.

But he thanked President Ma for his promise to protect the 87,000 Filipinos working in Taiwan after a Filipino worker there was attacked with a baseball bat amid public fury.