The Sri Lankan government says that Norway can no longer serve as a mediator between it and the Tamil Tigers.
The announcement comes a day after pro-rebel demonstrators trashed the Sri Lankan embassy in the Norwegian capital, Oslo.
The demonstrators - who videotaped themselves and posted the clip on the internet - escaped arrest.
In these circumstances, the Sri Lankan foreign ministry says, "it is no longer feasible for Norway to act as facilitator in the peace process".
That means Norway can no longer effectively play a role as one of four mediators, alongside the United States, Britain and Japan, in Sri Lanka's all-but-dead peace talks.
The ministry said Norway had shown "sheer neglect" of its obligations by failing to protect the embassy despite repeated requests for better security since protests have been on the rise in numerous world cities where there are large Tamil populations.
Norway brokered 2002 ceasefire
Sri Lanka's military has encircled the Liberation Tigers of Tamil Eelam (LTTE) in a 17 sq km strip of northeastern coast along with tens of thousands of civilians, and is aiming to crush the separatists and end a 25-year war.
Norway brokered a 2002 ceasefire between the Tigers and the Sri Lankan government, but the truce was shattered by renewed violence in 2006.
In diplomatic circles, Norway's role is valued because it has the best direct links to the Tiger leadership, and is usually the channel through which the mediators and international community make their positions or requests known.
That, however, has infuriated Colombo, which says Norway has no business contacting leaders of a group that the European Union - along with the United States, Canada and India - lists as a terrorist organisation.