The Ukrainian parliament on Thursday authorised the deployment of foreign forces to maintain peace and security, headed either by the UN or the European Union (EU).
The law precludes participating in peacekeeping operations for any country involved in the "military aggression against Ukraine", a clear reference to Russia, which Kiev accuses of arming the separatist militias in the east of the country.
A total of 240 deputies supported the ruling party's legislative initiative, which stated that the deployment of foreign troops should be upon the request of Ukraine, Efe news agency reported.
The Ukrainian constitution expressly prohibits the deployment of troops and establishment of military bases from other countries, so that each case must be approved by a separate law.
This is why the Ukrainian deputies also approved in March a law allowing the deployment of US and Polish troops to conduct military manoeuvres, after which those countries and Britain operated in the west of the country.
Ukrainian President Petro Poroshenko advocated deploying the forces in eastern Ukraine and the Russian border, which both the separatists and Moscow strictly oppose.
The law was passed after heavy fighting on Wednesday erupted in the Donetsk region between government forces and pro-Russian militias.
In his annual address to the parliament, Poroshenko reported on Thursday that the country was threatened by a full-scale war with Russia, which allegedly kept more than 9,000 soldiers in Ukrainian territory.
