"With the help of CCTV footage and the recently established (police) intelligence network we arrested the suspects along with the stolen goods," senior superintendent Athula Weerasinghe said.
The violence which erupted in the coastal resort of Alutgama spilled over into the neighbouring international tourist resorts of Beruwala and Bentota.
Weerasinghe said jewellery worth more than 1.5 million rupees ($11,500) looted from two jewellery shops in Bentota was recovered. Official estimates the riot damage at 200 million rupees. Four people were killed and 80 wounded in the worst religious riots in recent decades.
Sri Lanka's media as well as rights groups have accused the police of failing to prevent extremist Buddhist mobs attacking Muslims who constitute 10 percent of the country's 20 million population.
Police, however, said investigations showed there was a strong criminal element that fuelled religious tensions. Earlier, police had arrested 55 suspects including both Buddhists as well as Muslims, but the eight arrested this week are the first to be held for looting and directly involved in attacking shops.
The announcement of the latest arrests came as the Muslim Council of Sri Lanka (MCSL), an umbrella group of 48 Muslim organisations, petitioned police chief N. K. Illangakoon expressing fears of more violence against their minority community during the holy fasting month of Ramadan.
"We are concerned that the root causes to the problems related to the attacks on the Muslim community and other minorities has not been addressed and appropriate action taken to enforce justice," the MCSL said. MCSL president N. M. Ameen told AFP they would mark Ramadan in a low key because of the fear of more hate attacks.
Last week, Muslim-owned businesses shut down in Sri Lanka's capital to protest against deadly riots by extremist Buddhists.Muslims as well as a majority of moderate Buddhists have pressed for action against the Buddhist Force, or BBS, which is seen as enjoying patronage of senior government figures.