South Africa has deployed more than 3,000 soldiers across the country to reinforce security as anti-migrant protests intensify, with organisers vowing to stage demonstrations every week.

The military deployment, authorised by President Cyril Ramaphosa, began at the end of June and will support police in responding to any unrest.

Thousands marched through major cities earlier this week, with some protests turning violent as shops were looted and clashes broke out.

More than 900 people were arrested for offences ranging from immigration violations to public violence and robbery.

The demonstrations follow months of tension that have forced many migrants to flee their homes and businesses amid growing hostility.

Protest organisers say they are demanding stricter action against undocumented migrants, while rights groups warn the campaign is fuelling fear and violence against foreign nationals.