Defence Secretary Gotabhaya Rajapakse has asked the law and order ministry to deal with racial and religious hatred being spread using Facebook and Twitter, military spokesman Ruwan Wanigasooriya said.
"There are some Facebook pages against Buddhism, but more pages against Islam," Wanigasooriya told AFP. "Some try to project every Muslim as a jihadist. It is wrong and it must stop."
He said Rajapakse, the powerful younger brother of President Mahinda Rajapakse, had asked law enforcement authorities to work out a "practical way" of dealing with online hate speech.
Anti-Muslim riots in Buddhist-majority Sri Lanka two weeks ago left at least four people dead and 80 seriously wounded. Hundreds of shops and homes were also destroyed in the tourist resort towns of Alutgama and Beruwala.
Police have arrested eight suspects accused of looting during the riots, along with 55 others who have been linked to the violence.
The hardline Buddhist Force (BBS), which denies instigating attacks against Muslims, said last week that its social media pages had been blocked by service providers and their websites had been attacked by hackers.
There is no official censorship in Sri Lanka, but government authorities routinely block access to opposition and dissident websites.
However, the blocked sites can still be accessed through proxy servers based outside the country.
Sri Lanka's media as well as rights groups have accused the police of failing to prevent extremist Buddhist mobs attacking Muslims, who make up 10 percent of the country's 20 million population.
The influential Muslim Council of Sri Lanka, an umbrella group of 48 Muslim organisations, petitioned police chief N. K. Illangakoon last week expressing fears of more violence against them during the holy month of Ramadan.
Muslims as well as moderate Buddhists have pressed foraction against the BBS, which is seen as enjoying the patronage of senior government figures.
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