TUNIS (Reuters) - The European Union said on Tuesday it was concerned about the wave of arrests of many civil society figures, journalists and political activists, and demanded clarifications from Tunisia as the North African country faces a growing political crisis.

Tunisian police stormed the bar association's headquarters on Monday for the second time in two days and arrested Mahdi Zagrouba after detaining Sonia Dahmani, another lawyer critical of the president, over the weekend.

Some opposition parties and national organisations described the weekend raid as "a shock and major escalation," and the bar association declared a nationwide strike.

That day, two IFM radio journalists, Mourad Zghidi and Borhen Bsaiss, were also arrested following their comments on radio and social media, their lawyers said.

"Freedoms of expression and association, as well as the independence of the judiciary, are guaranteed by the Tunisian Constitution and constitute the basis of our partnership," the EU said in statement.

Last week, police arrested civil society activists including Saadia Mosbah on suspicion of helping sub-Saharan migrants stay in Tunisia and for alleged financial abuses, according lawyers.

Tunisian President Kais Saied said this month during a meeting of the National Security Council that the migrant situation raised questions about who was really behind it.

He called officials who run civil society groups defending migrants' rights "traitors" with foreign funding.

Saied took office following free elections in 2019, but two years later he shut down the elected parliament and ruled by decree.

He also assumed authority over the judiciary in what the opposition calls a coup. Saied claims his steps are legal and necessary to end years of chaos and corruption.

On Sunday, hundreds protested in the Tunisian capital to demand the release of imprisoned journalists, activists and opposition figures, and the setting of a date for a fair presidential election.

(Reporting by the Tunisian newsroom; Editing by Richard Chang)