Ukraine's Pro-Western political parties on Friday agreed to make joining NATO a priority in a coalition deal that will give them a parliamentary majority.

The coalition agreement between the five parties stipulates that a law must be passed by the end of the year confirming Ukraine's intention to push for membership of the military alliance.

A convoy of international monitors from the Organization for Security and Cooperation in Europe (OSCE) was shot at by "uniformed personnel" in east Ukraine, the organization said Thursday.

The OSCE said that a uniformed man on the back of a flat-bed cargo truck fired two shots in the direction of their vehicles as they were driving on Wednesday afternoon near the government-held town of Mariinka, some 15 kilometers (nine miles) west of the rebel stronghold of Donetsk.

When Igor Romanenko's friend suggested heading to a gathering on Kiev's Independence Square a year ago Friday, he had no idea he was about to witness the birth of a movement that would change his country forever.

The sandy-haired film director was angry and disappointed at the announcement that then-president Viktor Yanukovych had turned his back on a landmark deal with the European Union in favour of closer ties with Russia. 

Russia on Wednesday called for Ukraine to stay out of the NATO alliance, insisting that a "non-aligned status" was in the interests of the ex-Soviet country.

"There is no doubt that (Ukraine's) non-aligned status is important not only from the point of view of ensuring stability in the European Atlantic but also from the point of view of fundamental national interests of the Ukrainian people," Foreign Minister Sergei Lavrov told reporters.

A rebel leader in east Ukraine on Wednesday challenged President Petro Poroshenko to a duel, claiming it could bring peace to the war-torn region.

Igor Plotnitsky, the 50-year-old leader of the self-proclaimed Lugansk People's Republic, wrote an open letter to Poroshenko suggesting the whole nation could even watch the duel on live TV.

Leading critics of President Vladimir Putin on Tuesday urged Britain to step up pressure on the Kremlin chief by imposing sanctions on visiting Russian government officials and oligarchs.

Former prime minister Mikhail Kasyanov, members of the punk rock band Pussy Riot and environmental campaigner Evgenia Chirikova also urged Western leaders to stay united against Russia over Ukraine.

Ukrainian security services claimed Tuesday to have thwarted a plot against the Dutch foreign minister as he paid his respects to the victims of downed Malaysia Airlines flight MH17.

The alleged plot against Bert Koenders dates back to November 8 in Kharkiv, eastern Ukraine, where he and a delegation were due to visit a building housing the remains of some of the victims.

Ukraine's prime minister on Tuesday called for fresh talks with Russia on "neutral territory" as deadly fighting rumbled on in the country's east.

"We invite the Russian Federation to hold serious negotiations on a neutral territory. The US and EU are helping us with this," Arseniy Yatsenyuk was quoted as saying by the Interfax Ukraine news agency.

NATO warned on Tuesday of a "very serious" build-up of Russian soldiers and weapons inside Ukraine and on the border, as Germany's foreign minister urged Kiev and Moscow to respect a tattered peace plan.

The West is keeping up intense pressure on Russia over Ukraine following a bad-tempered G20 summit in Australia at the weekend which Russian President Vladimir Putin left early.

Six Ukrainian soldiers were killed and nine injured in fighting between government forces and Russian-backed rebels over the past day, the Ukrainian military said Tuesday. 

"In the course of the last 24 hours, six Ukrainian servicemen were killed and nine injured," military spokesman Andriy Lysenko said.