Indonesian prosecutors are demanding that a Singaporean boat captain, caught trespassing in Indonesia's waters, be jailed for eight years and his vessel blown up and sunk under the country's fishery laws.

Captain Shoo Chiau Huat, who had seven Singaporeans and six Malaysians on board Selin as passengers, was caught on April 16 in Tanjung Berakit waters, off Bintan island. He is also facing a 1.5 billion rupiah (S$152,000) fine.

All the passengers were deported about a week after the arrest.

Prosecutor Yuri Prasetyo told The Straits Times that he will officially read out the demand against the defendant, Mr Shoo, before the Tanjung Pinang district court today or later this week.

"We are seeking maximum punishments under the 2004 fishery law," Mr Yuri said, adding that the official demand letter from the Attorney-General's office in Jakarta would be sent to his office soon.

"It was a tugboat that had been modified to be a fishing vessel and it entered Indonesia without permits. The boat had fishing nets around it," Mr Yuri argued, to back his charges against Mr Shoo.

Mr Herman Black, the lawyer for the Singaporean, however, told The Straits Times that the penalties sought by the prosecutors are excessive and do not reflect the good, neighbourly relations between Indonesia and Singapore.

Mr Herman questioned the move to prosecute his client, as the case, he argued, was just a common, tourism-related trespass, explaining that his client was carrying tourists to do recreational fishing within Singapore waters but the boat drifted towards Indonesian waters.

In many countries that border one another, anyone entering the other country by mistake or because of unpredictable weather should immediately be deported, Mr Herman also argued. He said that there have been many cases of Indonesian and Malaysian fishermen being deported because of this.

"Why are they charging my client with the fishery law? My client's boat is only a recreational fishing boat. The evidence they seized was only 20 fish in total, meaning each person on board roughly got about one fish," Mr Herman added.

Mr Shoo had earlier told the court that he was hired by a person in Singapore he identified as Michael Tan, whose company, Marine Tourism, charges clients $3,800 for a boat trip.

Correction note: A previous version of this article said the boat captain's name was Choo Chiau Huat. This has been corrected to Shoo Chiau Huat.