(CNN) -- Norway has condemned the ransacking of the Sri Lankan embassy in Oslo by Tamil demonstrators.
The entrance to Sri Lanka's embassy in Oslo showed damage on Sunday.
Video posted on Norway's TV 2 Web site showed demonstrators smashing through re-enforced glass at the embassy on Sunday. The aftermath showed embassy offices that had been trashed, with furniture, artwork and potted plants dumped on the floor. Countertops had been bashed and splintered.
"Please help the Tamils. Stop the massacre of Tamils," a sign carried by one of the demonstrators said.
The foreign ministry said it has requested that police tighten security at the embassy, which is located in an office building.
"I deeply deplore the fact that unauthorized persons unlawfully forced their way into the Sri Lankan embassy in Oslo and caused extensive damage," said Foreign Minister Jonas Gahr Store. "This is a violation of Norwegian law and an action that is totally unacceptable."
Rohitha Bogollagama, Sri Lanka's foreign affairs minister, called for authorities to "seek immediate arrest of the perpetrators of this serious act of terror" during a CNN interview in New Delhi, India.
The attack came as Sri Lanka's president ordered military troops to restrict their offensive against Tamil Tiger rebels, while the nation celebrates the Sinhala and Tamil New Year. The two-day celebrations began Monday.
The order was meant to allow the thousands of Tamils trapped by the fighting to travel for the New Year, said a statement from the office of President Mahinda Rajapakse.
Troops are in the midst of an intense military push in northern Sri Lanka, where they have snatched back large swaths of land from the Tamil rebels.
The rebels have fought for an independent homeland for the country's ethnic Tamil minority since 1983. The civil war has left more than 70,000 people dead.
A statement on the Sri Lankan defense ministry Web site called on Norway to "bring the perpetrators to justice immediately."
"The perpetrators can be readily identified on the CCTV recording which has been made available to the authorities," the statement said. "The demonstrations, which had been building up in intensity in the past few days, provide an indication that something was being planned."
CNN's Harmeet Singh and Iqbal Athas contributed to this report