Trades unionists are being drawn into “the orbit of extremism”, a leading anti-boycott activist has warned.

Roger Lyons, chairman of Trade Union Friends of Israel, condemned plans to take a delegation of major union representatives to Gaza alongside the Palestine Solidarity Campaign.

Speaking ahead of this week’s Trades Union Congress conference in Bournemouth, Mr Lyons said the trip would bolster Hamas.

Delegates at last year’s conference had voted unanimously to back a Gaza trip. A report prepared for this week’s congress said preparations for the visit were ongoing.

Mr Lyons said the PSC had failed to support the current peace talks and was “hostile to the existence of Israel”.

“Without doubt the TUC visit to Gaza will give pleasure to Hamas, which is currently isolated and friendless, especially since the Egyptians have destroyed the tunnels and closed entry to Gaza,” he said.

“I am urging those unions being drawn into the orbit of extremism to re-think and withdraw. The TUC should respond to the ongoing peace negotiations which are supported by the Palestinian trade unions.

"Our priority is to build solidarity with the Palestinian and Israeli trade unionists, not the extremists."

The annual TUC event has traditionally been used to promote anti-Israel measures, but no boycott policies were moved this year.

Tufi director Steve Scott said many unions had “exhausted the policy area”.

“There is still a lot of chipping away at Israel, but they have other things higher on the agenda right now. There are a lot of industrial issues, coalition-bashing and discussions on the Labour links," he said.

“There’s always a black cloud over us here, but this year gives us a chance to discuss the peace talks, Histadrut and other issues relating to Israel."

Mr Scott said Labour supporters from Bournemouth’s Jewish community had attended the congress, volunteered on the Tufi stall and helped organise Tuesday’s Tufi fringe event.

That session featured a panel debate on ways to bring Israeli and Palestinian workers together and the prospects for the peace talks. It featured Hannah Weisfeld, director of grassroots advocacy group Yachad.

The speakers discussed developments in the Histadrut – Israel’s General Federation of Labourers – which has welcomed 21,000 new members in the past year, and increasing union growth in Israel, including for workers at McDonald’s and IKEA.

The PSC held its own fringe event opposing “Israeli racism and apartheid”. It was backed by a number of leading unions including Unite, Unison, the Fire Brigades Union, train drivers’ union Aslef, and the RMT.

Speakers included Palestinian footballer Mahmoud Sarsak who spent three months on hunger strike last year after being detained by Israel on suspicion of being an Islamic Jihad activist.