Russian President Vladimir Putin has signed into law the treaty formally making Crimea part of the Russian Federation, after it was approved by the parliament, on the same day Ukraine capped a landmark alliance with the European Union.

All 155 senators present in Moscow's upper house voted on Friday in favour of the treaty, which was signed on Tuesday by President Vladimir Putin and representatives of the secessionist Ukrainian region.

The treaty creates two new Russian administrative regions, Crimea and the port city of Sevastopol, where Russia's Black Sea fleet is based.