The strikers are protesting the three-month suspension of the leader of the union of local UN employees for alleged political activity linked to the militant Hamas group.

Thousands of teachers also staged a rally Wednesday outside the headquarters of the local UN headquarters.

Hamas, which seized Gaza in a violent takeover in 2007, has had an uneasy relationship with the UN Relief and Works Agency, the largest independent body in the territory.

The Islamic militants, hampered by an Israeli border blockade and shunned by much of the world, often struggle to provide services to the territory’s 1.5 million people and rely on the UN agency to fill some of that void. The agency runs schools, clinics and food centers that serve hundreds of thousands of Gazans.

However, some in Hamas view UNRWA as an ideological rival, accusing the agency of promoting a Western way of thinking in its schools and summer camps.

Although Hamas did not organize the one-day teachers’ protest, officials made clear that the ruling militant group supported the effort.

The protest was ostensibly sparked by the three-month suspension of Suhail Al-Hindi, a teacher and head of the union of local UN employees. Last month, Al-Hindi appeared next to Gaza Prime Minister Ismail Haniyeh at a public event.

UNRWA bars its local employees from engaging in political activity and Al-Hindi was suspended for violating that ban.

The agency also demands that those running for office in the union keep their campaigning to issues involving labor relations. However, Gazan society is small and people’s political affiliations are usually well known.

The union first staged a one-day strike over Al-Hindi’s suspension last week.

The teachers’ strike affects some 220,000 students.

Gaza government spokesman Taher Al-Nunu demanded that Al-Hindi be allowed to return to work and that UNRWA reconsider its ban on political activity. “They must show full respect for the Palestinian political system and the customs of Palestinian society,” he said.

But Adnan Abu Hasneh, a spokesman for the UN agency, said the ban on political activities is being enforced without exception.