"The protocol was signed and approved in accordance with a procedure that does not contradict the state's constitutional order," Interfax quoted the Constitutional Court judgement as saying.

The ruling on a Communist Party bid to block World Trade Organisation membership enables the State Duma lower house of parliament to pick up the legislation on Tuesday after 18 years of tense negotiations.

The State Duma may ratify the legislation needed for comfirming Russia's WTO membership on Tuesday or prolong debates over several days.

Russia became the world's largest economy outside the trade group upon China's accession in 2001. President Vladimir Putin had in the past doubted the wisdom of joining the group.

But Moscow managed to resolve all bilateral trade disputes by the end of last year and now has until July 22 to ratify the so-called accession package according to WTO rules.

Russia will formally become the organisation's 156th member 30 days after notifying the body of its ratification.