WASHINGTON (Reuters) -Microsoft has fired four employees who participated in protests on company premises against the firm's ties to Israel as it wages war in Gaza, including two who took part in a sit-in this week at the office of the company's president.

Anna Hattle and Riki Fameli received voicemails informing them that they were fired, the protest group No Azure for Apartheid said in a statement on Wednesday.

It added on Thursday that two more workers, Nisreen Jaradat and Julius Shan, were fired. They were among protesters who had recently set up encampments at Microsoft headquarters.

Microsoft said the terminations followed serious breaches of company policies. In its Thursday statement, it said recent on-site demonstrations had "created significant safety concerns."

No Azure for Apartheid, whose name references Microsoft's Azure software, has demanded that the company cut its ties to Israel and pay reparations to Palestinians.

"We are here because Microsoft continues to provide Israel with the tools it needs to commit genocide while gaslighting and misdirecting its own workers about this reality," Hattle said in a statement.

Hattle and Fameli were among seven protesters who were arrested on Tuesday after occupying the office of company President Brad Smith. The other five were former Microsoft workers and people outside the company.

Smith has said Microsoft respected "freedom of expression that everyone in this country enjoys as long as they do it lawfully."

A joint media investigation published this month found that an Israeli military surveillance agency was making use of Microsoft's Azure software to store countless recordings of mobile phone calls made by Palestinians living in the Israeli-occupied West Bank and Gaza.

The investigation, conducted by the Guardian, Israeli-Palestinian publication +972 Magazine and Hebrew-language outlet Local Call, said Israel relied on Microsoft cloud for expansive surveillance of Palestinians.

In response, Microsoft said it was turning to law firm Covington & Burling LLP to conduct a review.

Other Microsoft workers have also protested the company's ties to Israel.

In April, Microsoft AI CEO Mustafa Suleyman's remarks were interrupted by a pro-Palestinian protesting employee during the technology company's 50th anniversary celebration over the firm's ties with Israel. That employee and another protesting employee were also subsequently fired.

Firms and educational institutions have faced protests over ties with Israel as the humanitarian crisis in Gaza from Israel's military assault has mounted, and images of starving Palestinians, including children, have sparked global outrage.

The latest bloodshed in the decades-old Israeli-Palestinian conflict was triggered in October 2023 when Hamas militants attacked Israel, killing 1,200 people and taking about 250 hostages, Israeli tallies show.

Israel's subsequent assault on Gaza has killed tens of thousands of Palestinians, caused a hunger crisis, internally displaced Gaza's entire population and prompted accusations of genocide and war crimes at international courts that Israel denies.