Tunisia expelled the head of the European Trade Union Confederation (ETUC) on Saturday after she took part in an anti-government protest organised by the country's UGTT union, one of Tunisia's leading political forces.

The UGTT said the expulsion was "shocking" and opened up a confrontation with labour unions around the world.

Tunisian President Kais Saied declared the ETUC's Esther Lynch "persona non grata" and said the Irish citizen must leave the country within 24 hours.

Lynch's participation in the protests and remarks she made were a "blatant interference in Tunisian affairs", the government said.

Thousands of members of the UGTT took to the streets of eight Tunisian cities on Saturday to protest against Saied's policies, accusing him of trying to stifle basic freedoms including union rights.

Addressing one of the protests, Lynch called for the immediate release of detained union officials.

"We condemn this shocking decision ... it not only contains a confrontation against UGTT, but rather a with the international union movement", Sami Tahri, the senior official in the UGTT, told Reuters.

He added that Lynch was being harassed and even prevented from leaving her hotel for dinner.

Saturday's mass protests marked an escalation in the union's campaign against Saied and followed its criticism of recent arrests of several anti-government figures, including politicians, a journalist, two judges and a senior UGTT official.

The arrests have raised concerns of a wider crackdown on dissent and prompted the U.N. Human Rights Office to call for their immediate release.

The UGTT, which has more than 1 million members and has brought the country to a virtual standstill during strikes, has said the government is trying to stifle freedom of expression in a bid to deflect attention from the country's economic troubles.

Saied, who shut down parliament in 2021, seizing most powers and moving to rule by decree before writing a new constitution, said this week that authorities do not target freedoms, but seek to hold everyone equally accountable.