Two people have been killed and scores wounded as Saudi police clashed with protesting foreign workers in a district of the capital, Riyadh.
A police statement said hundreds of people were arrested in the Manfuhah neighbourhood.
Video on social media websites showed security forces in riot gear using truncheons to disperse large crowds.
Last week police rounded up thousands of migrant workers after an amnesty linked to new employment rules expired.
Police said they intervened on Saturday after foreign workers in the Manfuhah district rioted, attacking Saudi and other foreign residents with rocks and knives.
Manfuhah is home to many migrants, mostly from east Africa.
One of the two people killed was a Saudi while the other was unidentified, police said. About 70 others were injured and there were some 560 arrests, officials added.
On Sunday, witnesses said police were surrounding the district while units from the National Guard and special forces were sent in.
Nearby, hundreds of men, women and children lined up with their belongings to board police buses taking them to an assembly centre before their deportation, AFP news agency reported.
Images showed other foreign workers leaving the Manfuhah area in taxis.
Last Monday, the authorities began rounding up thousands of illegal foreign workers following the expiry of a seven-month amnesty for them to formalise their status.
An Ethiopian was reported killed on Wednesday as Saudi police began moving illegal immigrants into camps. The government in Addis Ababa has said it is providing support for Ethiopian workers and is helping to repatriate its citizens.
Nearly a million Bangladeshis, Indians, Filipinos, Nepalis, Pakistanis and Yemenis are estimated to have left the country in the past three months.
Four million others obtained work permits before last Sunday’s deadline.
Saudi Arabia has the Arab world’s largest economy, but authorities are trying to reduce the 12% unemployment rate among native Saudis.
An estimated nine million migrant workers are in Saudi Arabia – more than half the workforce – filling manual, clerical, and service jobs.