By Subir Bhaumik BBC correspondent in Calcutta

The legislative assembly in India's north-eastern state of Manipur has passed a unanimous resolution to preserve the territorial integrity of the state at all costs.

After a marathon 11-hour meeting that ended just before midnight, the legislators said they will not tolerate any attempt to split up the state or merge any part of its territory with any neighbouring state.

The resolution calls for a constitutional provision that will make it impossible to alter Manipur's boundaries in future

A Naga separatist rebel group now negotiating with Delhi has been asking for a merger of Manipur's Naga-inhabited areas with the neighbouring state of Nagaland to create a greater Naga tribal state.

The resolution passed by the Manipur assembly after 11 hours of deliberation calls for necessary amendment to the Indian constitution to ensure the territorial integrity of the tiny state bordering Burma.

It calls for a constitutional provision that will make it impossible to alter Manipur's boundaries in future.

Violent protests

Even those Naga tribal legislators who attended the assembly session supported the resolution, though some chose to stay away.

The prospect of carving away the Naga-inhabited areas of Manipur and merging them with the neighbouring state of Nagaland has loomed large since the middle of last year when the Indian Government extended the ceasefire with the National Socialist Council of Nagaland (NSCN) to Manipur and other north-eastern states.

At the time, sensing that this could be a prelude to a merger of its Naga tribal areas with Nagaland, tens of thousands of Manipuris took to the streets, burning down offices of political parties and even the state assembly building.

Senior political leaders of Manipur were also attacked. Some suffered serious injuries and fled the state.

After a month of furious street protests in Manipur, Delhi finally withdrew the ceasefire and confined it to Nagaland.

But as the prospects of a settlement with the rebel NSCN brightens, apprehensions have begun to rise in Manipur again that some of the state's hill regions may be carved out of it and joined to Nagaland.