Taiwanese fishermen on Sunday (March 27) said a fishing boat was allegedly stopped by an Indonesian vessel in the Strait of Malacca on Saturday and forced to pay a "bribe" before it was released, and urged the island's government to issue a protest.

The incident, if proven, would be the second clash in a week between Taiwanese fishing boats and Indonesian patrol boats.

"It was almost like a robbery," Lin Han-chou, an official with the Tung Kang Fishermen's Association in Taiwan's southern county of Pingtung, said on Sunday, reported the semi-official Central News Agency.

Lin said the Taiwanese fishing boat, the Ting Sheng, was chased by an Indonesian military vessel in waters between Malaysia and Indonesia before it was stopped.

The military vessel fired warning shots in the air during the chase, Lin said, citing the skipper of the fishing boat.

The skipper said he was taken to the Indonesian vessel while Indonesian personnel checked the ship, and he was asked to pay US$300 (S$412) before the boat was released.

The incident took place just north of Sumatra Island as the Ting Sheng was heading to the Maldives after offloading its catch in Singapore on March 22, Lin said according to Central News Agency.

The location was not far from where two Taiwanese fishing ships registered in Pingtung, the Sheng Te Tsai and Lien I Hsing No. 116, were fired upon by Indonesian patrol vessels on March 21.

Satgas 115, an Indonesian government taskforce against illegal fishing, said in a statement on March 24 that its had fired at the fishing boats "in self-defence" as the Taiwanese vessels tried to ram it.

The vessels were caught poaching in Indonesian waters off Lhokseumawe in Aceh, said Mr Fred Lonan, a Satgas 115 official, adding that this area is within Indonesia's exclusive economic zone.

Both Taiwanese skippers have denied the accusation, saying that they were only passing through the Strait of Malacca on their way to Singapore.

Lin and Tsai Pao-hsing, an official with another Pingtung-based fishermen association, the Liuchiu Fishermen's Association, said Taiwanese fishermen were feeling anxious over the developments, Central News Agency reported.

The officials urged Taiwan's Fisheries Agency and the Ministry of Foreign Affairs to lodge a protest against the Indonesian government.

They also demanded an apology and compensation from Indonesian authorities.