Sunday's upcoming referendum on the Ukrainian peninsula is illegal in its current form, the chairman for the Organization for Security and Cooperation in Europe (OSCE) said Tuesday.

"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," OSCE Chairman Didier Burkhalter was quoted as saying in a statement.

"For any referendum regarding the degree of autonomy or sovereignty of the Crimea to be legitimate, it would need to be based on the Ukrainian constitution and would have to be in line with international law," he added.

Crimea parliament pushes independence

Earlier on Tuesday, Crimea's Parliament voted overwhelmingly in favor of adopting a declaration of independence from Ukraine. The vote about Sunday's referendum, which parliamentary speaker Vladimir Konstantinov said he expected to see passed with 80 percent support, could give Russia the option of not having to absorb Crimea while still keeping the peninsula in its sphere of influence.

The referendum on Sunday gives voters the option of Crimea either becoming part of Russia or remaining in Ukraine but with broader powers. Like the OSCE, Ukraine's interim government in Kyiv has declared the measure illegal. It has also announced plans to dissolve Crimea's parliament.

Burkhalter "ruled out the possibility of an OSCE observation of the planned referendum … as the basic criteria for a decision in a constitutional framework were not met."

OSCE military observers have for the past week been unable to enter Crimea. The peninsula has been under the control of Russian forces since the fall of pro-Moscow Ukrainian President Viktor Yanukovych after months of protests.

Germany, Poland to talk Crimea

Speaking to her fellow conservative Christian Democrat (CDU) lawmakers in Berlin on Tuesday, German Chancellor Angela Merkel indicated there was a need to take a tougher stance on Russia's incursion into Crimea. She insisted Moscow must not be allowed to get away with the "annexation" of the region, CDU party sources told media.

Merkel is slated to meet with Polish Prime Minister Donald Tusk in Warsaw on Wednesday, where the two will discuss the Crimea crisis, particularly Western Europe's reliance on Russian natural gas.

"I'll present our views unequivocally on the political threats tied to dependence on Russian gas and money," Tusk said Monday, adding that many Western nations, not just Germany, depend on Russia for energy.

Germany imports around a third of its oil and gas from Russia. Berlin is also Moscow's leading trade partner in Europe and third largest worldwide.

dr/jm (Reuters, AFP, AP, dpa)