The police forces of Singapore, Malaysia and Indonesia last week initiated discussions on trilateral cooperation to stem piracy in and around the Straits of Malacca.

Shipowners said they welcomed the move, but added the problem has not been underreporting by shipowners, as some have claimed, but local authorities who too often ignore the attacks because of their political sensitivity."The comment that shipowners don't report these, I think it's more the case that authorities turn a blind eye," one European shipowner said. "They say it's international water and it's somehow sensitive and just beat around the bush."

Another shipowner said even if the three nations do cooperate on patrols, which will not necessarily happen, the pirate vessels are much faster than police cutters.

Piracy is on the rise in Southeast Asia. In recent weeks there have been more calls for action against the threat. Some 61 cases have been reported in 1991, up from 33 the year before. Most of these were hit and run raids with pirates in search of cash and personal effects and little interest in the cargo.

The piracy issue is receiving strong attention in recent days in the region partly because of the attention given to it by Malaysia's prime minister at last week's summit of Southeast Asian nations. In an address he called for international funding to fight the problem.

"Is it too much to ask that those who use the passage and the maritime nations contribute toward the cost of keeping them free and safe," Prime Minister Mahathir Mohamad said.

Shipowners also are concerned that the attacks are becoming more violent.

"There is concern at the frequency and ferocity of the attacks," said Eric Ellen, director of the U.K.-based International Maritime Bureau, in a telephone interview. "Recently a master was bound to the mast and the ship

went undirected for several hours."

Mr. Ellen is scheduled to meet late in February in Kuala Lumpur with police and regional policy-makers to explore the problem and possible solutions. The former London policeman rates Southeast Asia as one of the world's two worst pirate spots along with the waters off Brazil.

Industry officials say the political sensitivity of the issue in Southeast Asia follows in part because most of the pirate attacks occur off Indonesia. Singapore is one of the largest ports in the world, but a very small country in size. And Singapore with 3 million people is sensitive to anything that might upset its powerful neighbor with 180 million people to the south.

Mr. Ellen concedes that political sensitivity has probably worked against a full airing of the problem.

''Politically it is sensitive and I don't deny that's the case," he said. He adds that what he invariably hears is government's saying it didn't happen in their territorial waters therefore it isn't there problem.

One shipping line contacted said it had one of its containerships attacked 18 months ago off the Nan Tay Islands in Indonesia. The company declined to be identified for fear the pirates might target them again.

The pirates boarded at 4 a.m. and surprised the captain, who put up a fight. The pirates hit him several times and then jumped overboard.

"They use small boats," he said. "They're so low you can't see them on the radar." The ship returned to Singapore. The captain was all right but he was upset enough to discontinue the voyage and fly directly home.

Cyrus Midora, Singapore managing director with Inchcape Shipping Services, said six months ago they found ropes hanging off the ship indicating there had been an attempt.

Richard Kendall, joint service manager for New Guinea Pacific Line, Columbus Line and Bank Line, said the problem is a major concern for many operators. So far his group has been lucky, he added.

Shipping lines cite several tactics they use to reduce their chance of getting hit. Mike Chia, Singapore-based regional manager with Thailand's Regional Container Lines, said their ships have instructions to sail well clear of trouble spots.

"As you move further out to sea, the likelihood is less," he said. "But in some of the intra-island areas you have no choice."

Carriers say they turn on all the deck lights, post extra watches and lock all the water-tight doors when navigating troubled areas, which include the Gulf of Thailand and the Phillips Channel of the Singapore Straits.

"If we can't eliminate them, we try to slow them down," Mr. Chia said. ''But under no circumstances should the crew resist pirates if they're armed."