Moscow, March 14 (IANS): Moscow is disappointed with the statement of the Organisation for Security and Cooperation in Europe (OSCE) over the upcoming referendum in Ukraine's Crimea, the Russian foreign ministry said Friday.

“In its current form the referendum regarding Crimea scheduled for March 16, 2014, is in contradiction with the Ukrainian Constitution and must be considered illegal," the OSCE website quoted its Chairman-in-Office Didier Burkhalter as saying Tuesday.

Moscow insisted that it considers the Sunday referendum completely legal, citing the Helsinki Act of 1975 which guarantees the right for all nations to decide freely their internal and external political status.

It also expressed regret that the Swiss chairmanship of the OSCE had turned a blind eye to the "anti-constitutional coup" in Ukraine and to the legitimacy of the new regime in Kiev.

"We hope the chairmanship's possible assessments of these issues will take the Russian point of view into account," the ministry said.

Moscow called on the bloc to drop double standards and accept the invitation of the Crimean authorities for a monitoring mission during the referendum, which would facilitate de-escalation of tension in that region.

On March 6, the Crimean parliament voted to join Russia and a referendum on Crimea's status would be held Sunday.

The crisis in the mostly Russian-speaking Crimea began in late February following the ouster of Ukrainian president Viktor Yanukovych.

Since the beginning of the Crimean crisis, Kiev has been accusing Moscow of exacerbating the situation by increasing troop movements in Crimea, which is also home to Russia's Black Sea Fleet.