Russian President Vladimir Putin dismissed Western criticism of Sunday's Crimean referendum as an example of double standards before signing a treaty for the region to join Russia.

"They have constantly tried to drive us into a corner for our independent stance, for defending it, for calling things their proper names and not being hypocritical," he declared.

"But there are limits and in the case of Ukraine our Western partners have crossed a line. They behaved rudely, irresponsibly and unprofessionally."

The Russian president said that "in people's hearts and minds, Crimea has always been an integral part of Russia."

He said that present-day Ukraine had been born as the result of an illegal secession from the Soviet Union and that it includes "regions of Russia's historic south."

However, Mr Putin said that Russia had no intention of intervening in Ukraine, stating: "We don't want a division of Ukraine. We don't need that."

He argued that the months of street protests that paralysed Kiev and led to the overthrow of President Viktor Yanukovych had been instigated by the West in order to weaken Russia.

And the Russian president called the current Kiev government illegitimate and driven by radical "nationalists, neonazis, Russophobes and anti-semites."

Ukrainian Foreign Ministry spokesman Evhen Perebinis responded: "Today's statement by Putin showed in high relief what a real threat Russia is for the civilised world and international security.

"It has nothing to do with law or with democracy or sensible thinking."

Ukraine's coup-installed Prime Minister Arseniy Yatsenyuk claimed that his security agencies have gathered "convincing evidence of the participation of Russian special services in organising unrest in the east of our country."

The State Duma in Moscow condemned US sanctions imposed against a small number of Russian and Crimean officials and challenged him mockingly to extend them to all 353 deputies who voted for 's resolution.

The treaty signed by President Putin and Crimean officials will need to be endorsed by Russia's Constitutional Court and ratified by both houses of parliament.

But Valentina Matviyenko, speaker of the Russian parliament's upper house, said that the procedure could be completed by the end of the week.