Some 40,000 public servants hired by Hamas are on strike in Gaza in a pay dispute that could test the resilience of the new Palestinian government.
The government was formed just weeks ago under the Islamist group's unity pact with President Mahmoud Abbas.
All government offices in the Hamas-controlled Gaza were closed as a result of the one-day strike, but hospital emergency rooms remained open and police continued to patrol the streets.
The new government, based in the West Bank city of Ramallah, infuriated public workers on Hamas's payroll by saying it would vet them before paying out salaries - a process that could take months.
The wage dispute has shown the fragility of the reconciliation agreement signed in April under which a government of technocrats was formed with the task of holding a national ballot within six months.
Earlier this month, Gaza's public sector union suspended protests that lasted nearly a week, saying it would resume its action if its members were not promptly paid.
Hamas hired the employees after seizing Gaza from forces loyal to the Western-backed Abbas in 2007, a year after winning a Palestinian election.
"This strike is a first step and an initial warning to the unity government," said Mohammed Seyam, the chairman of the Hamas-hired workers' union in Gaza.
"We want to be recognised as employees of the Palestinian Authority and merged into the main salary list. If there was no response from the unity government we will escalate our protests," he told Reuters.
Kidnappings add to pressure
Apart from the salary row, the apparent abduction of three Jewish students in the West Bank, which Israel has blamed on Hamas, is also threatening the recent reconciliation between Palestinian rivals.
Officials loyal to Mr Abbas have warned the unity deal could fail if Israeli charges against Hamas were authenticated. The group has neither confirmed nor denied involvement.
But Mr Abbas is also facing growing resentment because his security services have been collaborating with their Israeli counterparts in the search to locate the three missing Israelis.
Activists rallied in Ramallah, the Palestinians' political capital, demanding an end to security coordination and hurled stones at one police station.
Hamas-hired workers on strike are especially resentful because Mr Abbas's Palestinian Authority in Ramallah has been paying its own 70,000-strong workforce in Gaza, even though the majority of them no longer worked under Hamas rule.
Hamas itself has struggled to pay its staff in recent months due partly to a continued rigid blockade imposed on Gaza by both Israel and Egypt - one of the reasons why the group decided to sign the accord with Mr Abbas.
At Shifa hospital in Gaza City, at least 40 patients gathered outside out-patient clinics closed by the strike.
"We support the rights of employees to receive their salaries but we also want to get medical treatment. Unless my daughter is treated the condition of her broken arm may worsen," said Talal Awad.