"We want a clarification from the Norwegians if the peace process is still on," said defence spokesman Keheliya Rambukwella.
The demand was put in writing to Oslo, which brokered a ceasefire agreement in 2002, along with a letter to the Sri Lanka Monitoring Mission of Scandinavian truce observers to ask if the ceasefire remained in effect, said Rambukwella, who is also policy planning minister.
"We are waiting a response," he told reporters.
On Monday night, Liberation Tigers of Tamil Eelam (LTTE) chief Velupillai Prabhakaran declared he had no option but to press for an independent state for the island's Tamil minority concentrated in the north and east.
Asked if Sri Lanka was officially at war now, Rambukwella said the government was committed to peace.
"We are pursuing peace ... But we will respond if we are attacked," Rambukwella said.
The Tiger statement went back on a 2002 pledge to accept a federal solution under which the Tamils would enjoy broad autonomy -- a commitment