A decision to ban face coverings a week after more than 250 people were killed in a series of coordinated attacks on Easter Sunday, has drawn a mixed response with activists saying the move violated Muslim women's right to practice their religion freely.

The law that took effect from Monday did not specifically name burqas, niqabs or hijab worn by many Muslim women.

A burqa is an outer garment that covers the entire body and the face, a niqab is a veil that also covers the face, while a hijab covers only the hair.

A statement from President Maithripala Sirisena on Sunday, said the ban is to ensure national security and that no one should obscure their faces to make identification difficult.

Many in Sri Lanka, including the All Ceylon Jamiyyathul Ulama (ACJU), the top body of Islamic scholars in the South Asian island nation, have backed the move on security grounds.

The group had earlier issued guidance asking Muslim women to avoid wearing face veils in the public, but added it was opposed to legislation.