A Brexit party MEP has been heavily criticised after he called for foreign fishing vessels to be “given the same treatment as the Belgrano”, the Argentinian cruiser sunk by the Royal Navy with the loss of hundreds of lives.

Robert Rowland, a hedge fund manager, made the remarks in a tweet about “the restoration of sovereignty over our waters”, in celebration of a fellow MEP, June Mummery, joining the European parliament’s fisheries committee.

He wrote: “We are behind all our fisherman [sic] and the restoration of sovereignty over our waters. 200 miles of exclusion zone with any foreign fishing vessel given the same treatment as the Belgrano! Well done June. We are 110% behind you and will ensure you give ‘em hell on committee.”

Robert Rowland (@RowlandBrexitSE) We are behind all our fisherman and the restoration of sovereignty over our waters. 200 miles of exclusion zone with any foreign fishing vessel given the same treatment as the Belgrano! Well done June. We are 110% behind you and will ensure you give ‘em hell on committee. https://t.co/HqdgHTPM5W

The Liberal Democrat MEP Chris Davies, who was elected this week to chair the fisheries committee, called the remarks evil. “That’s calling for people to be killed, that’s calling for fishermen from another nation to die in our waters. That’s evil. That makes me sick to the stomach.

“Is that the sort of country these people want? Where we actually kill fishermen, who have been doing nothing more than what they have been doing for hundreds of years.”

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The sinking of the General Belgrano in 1982 was one of the most controversial episodes of the Falklands war, and resulted in the death of 323 Argentinian sailors.

Barrie Deas, chief executive of the National Federation of Fishermen’s Organisations, said the “intemperate language” was not helpful.

After Brexit, he said, “we would expect there would be non-UK fishing vessels operating in UK waters, but under conditions determined by the UK, just like any other independent coastal state. The model would be Norway. The EU has a relationship with Norway for 40 years where stocks are jointly managed. The quota shares, which are very important, are agreed annually. It’s a bit like a marriage, there are ups and downs, but every year there is an agreement.”

Rowland is the director of Bowdon Capital Limited, a hedge fund registered in 2014. His MEP term began last week, as one of 29 Brexit party MEPs led by Nigel Farage who caused offence by turning their backs on a performance of Ode to Joy at the parliament’s opening ceremony.

A spokesman for Farage declined to comment on the Belgrano remarks.

Contacted by the Guardian, Rowland said: “It was a tongue-in-cheek comment. A bit of bravado made in solidarity with Brexit party MEP June Mummery, who had just been physically fronted by a Lib Dem MEP for standing up for British fishermen.”

Mummery claimed on Twitter that Davies had “aggressively stuck his face in mine” and told her British waters belonged to the EU, following a fisheries committee meeting.

Davies, one of two British MEPs elected to lead influential parliament committees this week, said she was lying: “I’ve no idea what she is going on about.” Mummery had introduced herself at the end of the meeting, before “haranguing” him in a corridor, he said. “I had people all around me and there are witnesses to say her account is inaccurate.”