(CNN) -- At least 17 people were killed and 45 others wounded Monday when a female suicide bomber blew herself up at a camp where civilians had sought refuge from the fighting between government troops and Tamil rebels in northern Sri Lanka, the defense ministry said.
The attack occurred at a camp in Mullaittivu, where the government said it was providing refuge, medical care and sustenance to displaced civilians.
The account could not be independently verified because the government does not allow media access to the areas where it is fighting the rebels unless it is on guided tours.
In the past, both the government and the rebels have exaggerated casualty counts and their causes.
According to the ministry, the assailant arrived at the camp with other civilians seeking protection and blew herself up before she could be screened.
The government blamed the Tamil rebels for carrying out the attack on civilians who had rebuffed the rebels' orders to take up arms and fight troops.
Meanwhile, the rebels said on their Web site that the army had indiscriminately fired on civilians inside a "safety zone," killing more than 80 and wounding 200.
The civilians were fleeing into rebel territory when they were killed by soldiers, the Tamilnet Web site said.
Again, the account could not be verified.
More than 10,000 civilians have fled fighting between government forces and Tamil rebels over the past week, a "sudden increase" in people displaced by the violence, the government said Sunday.
Humanitarian groups say as many as 250,000 unprotected civilians are trapped in the area where the fighting is taking place, and the onslaught has intensified as government forces have closed in on the rebels. The aid agencies have asked for increased access to northern Sri Lanka, calling it a nightmarish situation.
The Tamil Tiger rebel movement is locked in a battle with government troops over its remaining strongholds in northern Sri Lanka.
The rebels have been fighting for an independent homeland for the country's ethnic Tamil minority since 1983.