COLOMBO (AFP) - Sri Lankan police said on Wednesday they had arrested 75 would-be asylum-seekers trying to leave for New Zealand illegally, including nine women, six children, and a suspected former Tamil Tiger guerrilla.

The group was arrested in the southern coastal town of Moragolla.

It was the first large-scale arrest of nationals in months after Australia, long a favourite destination for Sri Lanka's refugees, tightened its borders.

"These people were trying to leave illegally for New Zealand," a police statement said.

It said initial investigations showed they included a former fighter from the Sea Tigers naval unit of the Liberation Tigers of Tamil Eelam, who were defeated after decades of separatist war in May 2009.

The arrests came five days after Australia announced that no illegal boats had reached its shores for 50 days due to tighter border patrols.

Asylum-seekers, many of whom claim persecution at home over Sri Lanka's Tamil separatist conflict, have tried to travel to New Zealand by boat in the past. But neighbouring Australia has been a more favoured destination.

Sri Lankan police have arrested dozens of people for organising illegal boat trips to Australia, including several naval personnel - an embarrassment for Colombo, which had maintained there was no senior-level official collusion with the smugglers.

Last week Australia sent back to Sri Lanka 45 nationals who tried to enter the country illegally.