Greek authorities have transported more than 500 migrants to a port on the mainland in an effort to relieve strain on the island of Crete after a surge in arrivals from Libya.

Greece has rescued hundreds of migrants off its southern islands of Gavdos and Crete in five separate incidents since Friday, its coastguard said on Sunday.

Greece on Friday enforced a three-month freeze on asylum claims from migrants arriving by boat from North Africa, to stem a surge from Libya that the government has called an "invasion". The emergency legislation, approved by a majority of 177 out of 293 lawmakers, allows authorities to detain asylum seekers in camps for up to 18 months.