The authorities in Burma have imposed a night-time curfew in at least two towns in western Rakhine state as inter-communal violence continues to spread.
Fighting between Rohingya Muslims and ethnic Rakhine Buddhists has been reported in two more districts.
At least four people have been killed and more than 1,000 houses burned down since the clashes began on Sunday.
Police have deployed reinforcements in the townships of Min Bya and Mrauk Oo, where curfews are now in effect.
The BBC Burmese Service says at least one person was killed in fighting in Mrauk Oo on Wednesday.
Rakhine state spokesman Myo Thant said the fighting had now spread to the townships of Kyauk Phyu and Myebon, south of the state capital Sittwe.
"Houses are burning and clashes between the two communities are ongoing," he said.
"The most important thing is to put out the fires. We are trying to control the situation."
Tensions have remained high in Rakhine state since May when a Buddhist woman was raped and murdered by three Muslims.
A mob later killed 10 Muslims in retaliation, although they were unconnected with the earlier incident and the violence escalated after that.
In June, 90 people were killed as religious clashes spread across the state.
The houses of both Buddhists and Muslims were burnt down and thousands of people fled.
It is unclear what prompted the latest clashes. Muslims and Rakhine Buddhists blame each other for the violence.
The two communities are now almost completely segregated in towns such as Sittwe, where the Rakhine are able to roam freely while the Rohingya are mostly confined to a series of camps.
Muslims throughout Burma have abandoned plans to celebrate the festival of Eid al-Adha because of the violence.
There is long-standing tension between the ethnic Rakhine people, who make up the majority of the state's population, and Muslims, many of whom are Rohingya. The Burmese authorities regard the Rohingya as illegal immigrants.
In August Burma set up a commission to investigate the violence between Buddhists and Muslims in the west of the country. Authorities earlier rejected a UN-led inquiry.