Intimidation at sea and fishing with illegal nets cannot be accepted, the Minister for the Marine said. He promised to do his best to "stamp it out".

Mr Fahey told the Dail more than 50 incidents of intimidation and harassment had been reported to the Department in the last five years. A detailed review had taken place and while some were genuine collisions, "the majority of the incidents which occurred involved vessels protecting, or trying to protect, their own fishing gear".

He would be bringing legislative proposals to Government "in the very near future" to deal with such incidents.

Mr Fahey said he had asked the Naval Service and sea fishery officers to be highly vigilant. He said he took a very serious view of the issue because illegal fishing of this nature was detrimental to the conservation of fish stocks, already under pressure.

The Fine Gael spokesman on the marine, Mr Michael Finucane, said there was extreme concern in Castletownbere, Co Cork, that foreign fishing vessels were using undersized mesh. There were complaints as well about an incident some weeks ago when a 150 ft steel French trawler intimidated 70 ft wooden trawlers and was using gill nets up to 12 miles long.

"How seriously do we take this type of incident, given that the French trawler was allowed to get away?"

Mr Finucane added that the French trawler was arrested yesterday for fishing with illegal nets. He hoped that the Minister's promise would mean many more arrests for such intimidation and the use of illegal nets.

Mr Fahey said there was no evidence to substantiate Mr Finucane's allegations, but there had been complaints about the use of illegal nets. Checking gear type was standard practice of the Naval Service and the Department's control staff.

"There have not been significant instances of the use of illegal gear by foreign fishing vessels in the recent past," he said.