Trade unionist Mick Lynch has told a crowd of workers and activists that the “ultra right” is causing division during the cost-of-living crisis, and it should be resisted.

He also praised unions across Northern Ireland that had taken industrial action in recent months, and called for the trade union movement to begin in every town and county, saying that people were “ready for change”.

The general secretary of the Rail, Maritime and Transport union (RMT) said he has received a “tremendous” welcome as he met and marched with activists and trade unions through Belfast.

Mr Lynch rose to prominence last summer following a series of media interviews about a rail workers’ strike held in the UK in a long-running dispute over pay and conditions.

The trade union leader, whose father left Cork city in 1941 to travel to Britain to work, and whose mother is from Co Armagh, addressed a rally gathered at Belfast City Hall on Saturday.

Addressing trade union groups including Unison, Nipsa, Unite and the Northern Ireland Teachers Council, who have all taken industrial action in recent months, Mr Lynch said that the values of the trade union movement “are back on the agenda”.

He said that nurses in Britain “are on the move” towards industrial action following on from strikes by nurses in Northern Ireland, which was met with applause.

“The trade unionists on this island are the salt of the earth, and they’ve kept the movement going through thick and thin, through all the struggles that you’ve had, the struggles for peace and justice and democracy.

“It’s been the trade unions that have kept our spirits alive, that have kept this movement going, bringing all of our people together, no matter what their heritage, no matter what their background, and we have to keep doing it.

“Because we know what’s being said: the ultra right are going to exploit division.

“They’re seeking to do it in the south, they’re seeking to do it up here.

“They’re seeking to do it in England.”

He said that “open Nazis are trying to divide our people one from another”, by “trying to blame some of the poorest people in the world for our problems over here”.

“We cannot allow that to happen,” he said.

He added: “We’ve been going into the temples, the mosques, the synagogues, bringing everyone together.

“And that’s our task: to build a labour movement that reflects all of our working class people and brings them together behind our values and not allow others to exploit them and create that division.

“We have to celebrate our diversity.

“Diversity is wonderful, but solidarity and unity is powerful, and that’s what we got to build.”

He warned against authorities using global crises for denying workers better pay and conditions.

“They can dress it up wherever they want, they can blame it on the pandemic.

“They can blame it on the economy.

“Now they’re blaming it on a war in eastern Europe.

“What is to blame is capitalism, exploitation, the deliberate creation of poverty so that they can enrich themselves and we’ve got to stand up to that.”

As trade union members gathered in Writers’ Square ahead of the march through Belfast, Mr Lynch was asked to pose for pictures and selfies with workers bearing various trade union banners.

He was given a small bust of the founder of the Irish Labour party James Connelly, a book about the history of trade unions in Ireland and pinned a University and College Union badge given to him to his jacket.

As he began to address, he praised the prominence of women in Northern Ireland in the trade union movement, after the crowd was addressed by leaders including Unison’s Patricia McKeowan and Unite’s Susan Fitzgerald.

Ictu assistant general secretary Gerry Murphy said Mr Lynch was addressing the May Day march as “every trade unionist across these islands, and many outside our movement, have been inspired and encouraged by the wisdom and clarity offered” by Mr Lynch.

“In a series of media interviews which became internet phenomena, Mick ignored attempts to sideline the justified demands of his members by trivial and stereotypical questioning, and instead outlined their just cause for decent pay and working conditions with style and wit,” he said.

“By doing so, Mick has assisted trade union representatives from every sector of our economy and society to explain with clarity why so many working people are taking the principled and initially costly decision to vote for strike action.”

Speaking to the PA news agency ahead of his address, Mr Lynch said the warm welcome he received as he walked through the streets of Belfast with trade unions in Northern Ireland was not unusual.

Some people applauded the RMT general secretary as he held an Ictu banner and marched with workers towards Belfast City Hall, while one man went to shake his hand.

Mr Lynch told the PA news agency he tends to get a good reception across Britain and Ireland.

“People are reaching out to trade unions, they want to hear the message and they want to show their support. So it’s all good stuff.”

When asked does the support of punters put pressure on him personally to deliver a deal for the RMT, he said: “You’re always under pressure and that’s a good thing.

“You’ve got to deliver, and our members have shown their commitment to our campaigns, to our industrial action and it’s my job to get them a deal.

“We’re working on that, but we’ve got a very tough opponent. The Tories don’t want to give anyone anything, just 4-5% norm.”

He said that having all workers on zero-hour contracts would be “degrading”, saying: “We can’t have that, that’s a degrading of the workplace and it degrades society in the long run, so we’ve got to fight that, for our people.”

On Thursday, RMT said rail workers at 14 train operators would strike on the day of the Eurovision Song Contest final after the latest offer aimed at resolving the pay dispute was rejected.