On deck, four "trouble-makers" who mutinied are forced to sit through the searing day, legs crossed, hands behind their heads, forbidden by Royal Australian Navy guards to look around or speak.

A Navy bilge pump works 24 hours a day. Without it, the rotting Indonesian fishing boat that has become a prison hulk would sink.

Throughout the 30-degree days and humid nights, the regular tumpa-tumpa of the pump has become a heartbeat for 50-odd asylum seekers, who have been moored at Christmas Island for eight days, denied permission to land.

But the bilge pump is also their torment. Its job is to keep the decrepit 20-metre wooden boat afloat while engineers repair the diesel engine - apparently so the boat and its human cargo can be towed out to sea and sent back to Indonesia.

Due east and 2,000 kilometres closer to the Australian mainland, an RAN patrol boat guards a second hulk, anchored in the lagoon at Ashmore Reef where it arrived four days ago. It was the eighth boat to arrive in Australian waters since August.

On the 25-metre Indonesian vessel are 219 men, women and children for whom there is only one certainty: they will not be allowed to land on Australian soil. They, too, face the possibility of being towed back to sea.

At Christmas Island, the fishing boat has been moored 50 metres offshore at Smith Point since 6am last Saturday, when it was towed in by HMAS Warramunga with 222 asylum seekers - mostly Iraqis - and five Indonesian crew, who had been recruited by people smugglers.

Civilian stevedores provedored the boat during the weekend until the Navy took control at 5.30am on Monday. Women, children - including a one-month-old baby - and some men were transferred to the Warramunga. But about 50 men refused to leave.

The four "trouble-makers" were identified and isolated on deck under guard by armed sailors. "If they look around or speak, they cop it," a witness said. "It's rough."

The others are kept in the stifling heat below, allowed on deck in manageable numbers for exercise and relief.

In a week that saw more than 300 asylum seekers die when their boat sank, no-one, including the Navy, doubts the unseaworthiness of the boat at Christmas Island. Due for the wreckers ago, it leaked so badly that only the pump keeps it afloat. The timbers are saturated by ancient oil spills. On Tuesday there was a fire, quickly extinguished. It had been a coastal timber trader, not built for the open sea.

Navy engineers were unable to repair the diesel engine, which they claim was sabotaged, so civilian engineers were brought on board. They also failed, and there is talk of flying in a replacement engine.

"That boat is a death trap. It will sink," said Gordon Thomson, secretary of the Union of Christmas Island Workers. "So why is the RAN working night and day to fix the engine? Because they've been told to take it back out to sea, to send the asylum seekers back to Indonesia. It's criminal. It's against the law to send an unseaworthy boat to sea."

One Indonesian boat carrying about 200 asylum seekers was intercepted and towed back to Indonesian waters by the Warramunga two weeks ago.

Although Mr Howard said this was the preferred response, the Government refuses to explain its plans for the asylum seekers at Christmas Island and Ashmore. The Immigration Minister, Philip Ruddock, refers to a "range of options", which he will not outline.

But the Government has run out of islands to send the asylum seekers to. Nauru has taken its limit. Papua New Guinea has not agreed to take more. Fiji, Palau and Kiribati have offered bare-soil sites but it would take time to provide the infrastructure.

There is room on Christmas Island, however, for between 500 and 600 people, since 220 asylum seekers left for PNG on Monday. "We're not expecting a decision [about the boats and their passengers] for at least several days," an immigration spokesman said yesterday.