Communal violence is continuing in western Burma six weeks after the government declared a state of emergency, with much of it directed at minority Muslim Rohingyas who have been beaten, raped and killed, Amnesty International has claimed.

The rights group accused both security forces and ethnic Rakhine Buddhists of carrying out fresh attacks against Rohingyas, who are regarded as foreigners by the ethnic majority and denied citizenship by the government because it considers them illegal settlers from neighbouring Bangladesh.

After a series of isolated killings starting in late May, bloody skirmishes spread quickly across much of Burma's coastal Rakhine state.

The government declared a state of emergency on 10 June, deploying troops to quell the unrest and protect both mosques and monasteries. Authorities said at least 78 people had been killed and thousands of homes of both Buddhists and Muslims either burned down or destroyed.

Since then, communal violence has continued, albeit at reduced intensity. Amnesty said attacks were now being directed mostly at the Rohingya population.

Violence in the past six weeks has been "primarily one-sided, with Muslims generally and Rohingyas specifically the targets and victims", Benjamin Zawacki, a Bangkok-based researcher for Amnesty, told the Associated Press. "Some of this is by the security forces' own hands, some by Rakhine Buddhists, with the security forces turning a blind eye in some cases."

Officials from Burma's government could not immediately be reached for comment.

Amnesty also said security forces, including the police and the army, had detained hundreds of Rohingyas.

"While the restoration of order, security, and the protection of human rights is necessary, most arrests appear to have been arbitrary and discriminatory, violating the rights to liberty and to freedom from discrimination on grounds of religion," Amnesty said in a statement.

The violence, which reached its bloodiest point in June, constituted some of the country's deadliest sectarian bloodshed in years and raised international concerns about the fate of the Rohingyas inside Burma.

The Burmese president, Thein Sein, said earlier this month the solution to ethnic enmity in Rakhine state was to either send the Rohingyas to a third country or have the United Nations refugee agency look after them. The UNHCR chief, Antonio Guterres, said, however, it was not his agency's job to resettle the Rohingyas.

Many people in Burma do not recognise Rohingyas as legitimate settlers – even those of Bengali heritage who came in the 19th century when the country was under British rule. The exodus of Rohingyas to Bangladesh in the 1980s and 1990s because of persecution, and their subsequent return, has added to the confusion over who among them are illegal immigrants.

Bangladesh also denies the Rohingyas citizenship, arguing that they have been living in Burma for centuries and should be recognised as citizens there instead.

The UN estimates that 800,000 Rohingyas live in Burma. Thousands attempt to flee every year to Bangladesh, Malaysia and elsewhere, trying to escape a life of abuse that rights groups say includes forced labour, violence against women and restrictions on movement, marriage and reproduction that breed anger and resentment.

Amnesty called on Burma to accept Rohingyas as citizens, something the government has staunchly opposed because it does not consider them an ethnic group native to Burma.

"Under international human rights law and standards, no one may be left or rendered stateless," Zawacki said. "For too long Myanmar's [Burma's] human rights record has been marred by the continued denial of citizenship for Rohingyas and a host of discriminatory practices against them."