Sri Lanka has banned women from wearing face veils after more than 250 people - including eight Britons - were killed in a wave of suicide bombings.
The ban falls under an emergency law that was put in place after eight men and a woman carried out the Easter Sunday attacks at churches, hotels and a house raided by police.
Sri Lanka's government rejected criticism by saying the ban on face coverings would help security forces to identify people as they hunt for any remaining attackers and the support network.
There were concerns within the minority Muslim community that the ban could fuel tensions in the multi-ethnic island in the Indian Ocean.
Security officials have warned that Islamist militants behind the bombings are planning imminent attacks and could be dressed in military uniforms.
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The militants were targeting five locations for attacks on Sunday or Monday, security sources told Reuters.
In a letter to lawmakers, the head of the ministerial security division (MSD), a unit of the police, wrote: "There could be another wave of attacks.
"The relevant information further notes that persons dressed in military uniforms and using a van could be involved in the attacks."
Security across Sri Lanka has been ramped up with scores of suspected Islamists arrested since the April 21 suicide bombings.
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Sunday mass services were cancelled amid fears of further attacks.
Authorities suspect members of two little known groups - National Thawheedh Jamaath (NTJ) and Jammiyathul Millathu Ibrahim - of carrying out the Easter attacks, though ISIS has claimed responsibility.
Prime Minister Ranil Wickremesinghe said a tight-knit group of people was involved, mostly close friends and families.
He told Reuters: "They (the group) were small enough that they were not using normal (electronic) communications, instead meeting each other."
It is believed the bombers had guidance due to the coordinated bombings, the type of explosives used and the tightly guarded plot, he said.
The terrorists managed to carry out the attacks despite multiple warnings that weren't heeded by authorities.
The eight Britons who died in the attacks have been named as mum Anita Nicholson, 41, her son, Alex, 14, and daughter Annabel, 11; Daniel Linsey, 19, and his sister Amelie, 15; Sally Bradley, 56, and her husband Bill Harrop, 56; and Lorraine Campbell, 55.
The Foreign Office has warned against all but essential travel to Sri Lanka following the Easter Sunday bombings.
In the wake of the attacks, tourist arrivals in Colombo will fall by 50 per cent, Sri Lanka's tourism chief said.
