An angry Russia said on Thursday that it would consider pulling out of the Council of Europe, Europe's leading human rights body, following a vote to suspend it from the council's parliamentary assembly.

The council's assembly backed a resolution to withdraw the voting rights of Russia's 18-member delegation. The ban lasts until the end of 2014. The assembly also terminated Russia's right to participate in election observation missions and turfed it off its most prestigious committees.

The resolution, adopted by 145 votes to 21, with 22 abstentions, was passed after a heated three-hour debate in Strasbourg. Russian members stormed out of the chamber before the vote took place. The assembly condemned Russia's annexation of Crimea, its military occupation of Ukrainian territory, and Moscow's "illegal so-called referendum" on the peninsula. This – and Moscow's ongoing threat of "military force" – constituted "beyond any doubt, a grave violation of international law", the assembly declared.

The 47-nation Council of Europe is separate from the EU and oversees the European court of human rights. Unusually, it brings together parliamentarians from both western and eastern Europe, as well as the countries of the former Soviet bloc. Russia has been a member since 1996. The decision to suspend Russia may provoke a sharp response from the Kremlin.

Speaking at a chaotic, ill-tempered press conference after the vote, the head of the Russian delegation, Alexey Pushkov, said Russia would consider terminating its membership of the assembly. A decision would be made in "the next two or three weeks", Pushkov said.

Several of his colleagues launched a venomous attack on European countries that had moved to punish Russia. Some Europeans had adopted a "pathologically biased approach" and had treated Russia – a "great country" – in a scornful and condescending manner. "Since arriving here a year and a half ago I haven't heard a nice word said about the Russian Federation," one complained.

Pushkov declined a request to speak in English, although he did answer one question in French. "We speak Russian," he said defiantly. He accused the United States, not a member of the assembly, of adopting double standards, after bombing Belgrade in the 1990s and invading Iraq. "It [the US] doesn't have a moral right to comment on our behaviour," Pushkov said.

A group of Conservative MPs led by Robert Walter led a charge to suspend Russia fully from the assembly. His amendment was defeated but another compromise resolution, based on a report by Austrian Stefan Schennach, was passed. It said Russian delegates should be suspended "in order to mark condemnation and disapproval of the Russian Federation's actions with regard to Ukraine". Russia is now barred from three important assembly bodies: its bureau, its presidential committee – made up of six or seven top figures – and standing committee.

The assembly said that Russia could be further punished with its credentials annulled if it did not reverse the annexation of Crimea and de-escalate the febrile situation in Ukraine. For the moment, however, delegates agreed that "political dialogue" with Russia was the best way to find compromise. There "should be no return to the pattern of the cold war", it concluded.

The council's parliamentary assembly has suspended the voting rights of the Russian delegation once before, from April 2000 to January 2001 over the situation in Chechnya. There have been other challenges, but in these cases the assembly reconfirmed Russia's credentials after a debate.