Fighting resurged in Rakhine in early December between government forces and the rebel Arakan Army, which wants more autonomy for the Buddhist ethnic Rakhine minority.
It was also in the restive western state that a military-led crackdown in 2017 prompted hundreds of thousands of minority Rohingya Muslims to flee westwards to neighbouring Bangladesh.
The separate conflict between the military and Arakan Army rebels forced 2,500 civilians from their homes by the end of last year, according to the United Nations.
Myanmar military spokesman Zaw Min Tun said earlier the insurgents had hit police outposts in a rugged region near the border with Bangladesh.
"These police posts are there to protect the national races in the area so (Arakan Army rebels) shouldn't attack them," Zaw Min Tun said, referring to mostly Buddhist ethnic groups in the area who are, unlike Rohingya Muslims, considered Myanmar citizens.
Arakan Army spokesman Khine Thu Kha confirmed the assault and said rebels later retrieved the corpses of seven "enemies".
He said later that rebels had freed at least 12 members of the security forces it detained in the fighting.
The attacks, he added, came in response to a Myanmar military offensive against the Arakan Army in recent weeks that had also targeted civilians.
The Myanmar military last month announced a four-month halt to fighting in the north and northeast of the country to kick-start peace talks with multiple armed groups seeking ethnic autonomy, but that announcement excluded Rakhine state.
Friday's violence erupted shortly after the national flag was raised across the southeast Asian country to mark 71 years since independence from Britain, but the Arakan Army spokesman denied any connection between the attacks and the anniversary.
"We are not independent yet. Today is not our Independence Day," Khine Thu Kha said.
Last August a U.N. report accused the Myanmar military of mass killings and rapes of Rohingya with "genocidal intent" in 2017 in then operation that drove more than 700,000 of them to flee to Bangladesh, according to U.N. agencies.
Myanmar has denied the charges, saying its military launched a counter-insurgency operation after attacks on security posts by Muslim militants.
(Reporting by Thu Thu Aung and Shoon Naing Writing by Simon Lewis Editing by Nick Macfie and Mark Heinrich)
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)