Sri Lanka ordered tens of thousands of security personnel to secure public schools ahead of their reopening Monday, officials said, following the Easter suicide bombings.
The search for explosives and a security cordon thrown around 10,900 schools nationwide came as the government said it has expelled over 600 foreigners, including around 200 Islamic clerics, since the April 21 attacks claimed by the Islamic State group.
Police spokesman Ruwan Gunasekera said "police and soldiers combed school premises and the surrounding areas to make sure it is safe for children to go back" on Monday.
As part of the clampdown after the attacks on three churches and three luxury hotels, the government announced a crackdown on foreign Islamic clerics operating in the majority Buddhist country.
Home Affairs Minister Vajira Abeywardena said 200 clerics were found to have overstayed visas, for which fines were imposed and they were then expelled.
"Considering the current situation in the country, we have reviewed the visas system and took a decision to tighten visa restrictions for religious teachers," Abeywardena told AFP.
"Out of those who were sent out, about 200 were Islamic preachers."
The suicide attacks were led by a local cleric who is known to have travelled to neighbouring India and made contact with jihadists there.
The minister did not give the nationalities of those who have been expelled, but police have said many foreigners who have overstayed their visas were from Bangladesh, India, Maldives and Pakistan.
"There are religious institutions which have been getting in foreign preachers for decades," Abeywardena said. "We have no issues with them, but there are some which mushroomed recently. We will pay more attention to them."
The minister said the government was overhauling its visa policy following the attacks.
Sri Lanka has imposed a state of emergency since April 21 and given wide powers to troops and police to arrest and detain suspects. About 150 people have been taken into custody.
House-to-house searches are being carried out across the country looking for explosives and propaganda material of Islamic extremists.