"We have reports of a hartal (work stoppage) on Monday," Rohana told AFP. "We are making arrangements to ensure that there is no trouble. There will be tighter security."
He dismissed the barrage of media criticism Sunday that police should take the blame for anti-Muslim riots carried out by hardline Buddhists a week ago which left four people dead, 80 wounded, and hundreds of homes and shops destroyed.
"It is unfair to blame one individual, there are so many factors involved," Rohana said, referring to a call for Inspector General of Police (IGP) N. K. Illangakoon to step down.
The privately-run The Nation weekly took the unusual step Sunday of leading its front page with an editorial, with the blunt headline: "The IGP must resign".
Other media joined in blasting officials for failing to rein in a hardline Buddhist group known as the Bodu Bala Sena (BBS or the Buddhist Force), blamed for much of the unrest.
"Arrest him," the Sunday Leader newspaper demanded in a headline, referring to the head of the BBS, Galagodaatte Gnanasara, who has publicly denied causing trouble.
Sri Lanka's Sunday Times said the burning down of the Muslim-owned No-Limit clothing store outside Colombo on Saturday "is an indication that some people might want this violence to spread".
Police were investigating the cause of the blaze, which Justice Minister Rauf Hakeem, the most senior Muslim in President Mahinda Rajapakse's cabinet, described Saturday as an arson attack.
Rohana said forensic experts were expected to visit the charred building on Monday.
- Government accused of links to BBS -
The Sunday Times said a majority of Buddhists in the country did not support the extremist views of the few monks who were behind the hate campaign, and that they should be dealt with before the unrest escalates further.
Some reports also echoed charges by the main opposition United National Party that patronage by senior government figures may have held police back from acting against the BBS.The UNP has accused the country's powerful defence secretary and president's younger brother, Gotabhaya Rajapakse, of backing the BBS.
Gotabhaya Rajapakse had opened a Buddhist cultural centre at the southern town of Galle in March last year in the company of BBS leaders, while President Mahinda Rajapakse opened a Buddhist centre with a BBS leader in Colombo in April 2011.
Justice Minister Hakeem has strongly criticised the BBS and has asked the president to order an independent probe into last week's riots targeting Muslims, who account for some 10 percent of Sri Lanka's population of 20 million.
Hakeem, in a statement issued on Saturday night, blamed the government for failing to control the BBS, which last year led a successful campaign to take halal certification off food sold to non-Muslims in the majority-Buddhist nation.
"Irrespective of who is responsible for the terrible events that unfolded... none would dispute that it was a serious dislocation of the ability of the state to maintain the rule of law," Hakeem said after an emergency meeting Saturday with the president.
The president has said he is ordering a probe into "recent disturbances".