The Sudanese army confirmed troop movements in the area where the rebels said they carried out their attack on Tuesday but gave no further details.
A source in the aid community confirmed an attack on a police station in the town of Sirba and said three police officers had been wounded.
The rebels, the breakaway National Movement for Reform and Development, (NMRD) are not represented at the African Union-sponsored talks in Abuja and say they no longer respect a ceasefire they signed with the government, after Sudanese armed forces attacked their positions near the border with Chad.
"This morning at 6.30am (0330 GMT) we attacked and took control of Sirba town in West Darfur. We are now in control of the town," Khalil Abd Allah, the political leader of the group, said from Darfur.
He said the rebels had killed 37 troops and police and taken six vehicles.
"For one year we are co-operating with the African Union and still we are not part of the negotiations in Abuja," he said, giving as the reason why the group had attacked the town.
Abd Allah said the group was also retaliating for government strikes on their bases in the Jabel Moun area near the Chadian border earlier this month.
He said the more than 6000 AU troops monitoring a shaky ceasefire in the remote west of Sudan were doing nothing to rein in Khartoum's security forces.
"This morning at 6.30am (0330 GMT) we attacked and took control of Sirba town in West Darfur. We are now in control of the town"
Khalil Abd Allah,
Leader of the National Movement for Reform and Development
The NMRD's demand to take part in the Abuja peace talks came as representatives of the two main Darfur rebel groups and the government prepared to open the seventh round of negotiations on Tuesday.
But observers are sceptical that the talks will produce any concrete developments, and say one reason is insufficient representation of those fighting in the field.