KIEV, July 17 - Ukraine's president accused Russia's military on Friday of ordering the missile strike that brought down Malaysia Airlines flight MH17 one year ago, as relatives gathered from the Netherlands to Australia to remember the 298 passengers and crew.

"MH17, where 298 victims were killed for no reason, was shot down by a Russian BUK missile, launched by a Russian professional crew under an order and an instruction from the Russian military," President Petro Poroshenko said on the first anniversary of the disaster, Reuters reported.

Ukraine has consistently blamed Russia, but Poroshenko's comments were his most direct to date.

Russia denies responsibility and in turn has pointed the finger at Ukraine, whose forces are fighting pro-Russian separatist rebels in the region of eastern Ukraine where the plane crashed to earth.

Poroshenko did not say what evidence he had for accusing the Russian military. In comments later on Friday, he used a different form of words, blaming the tragedy on Russian-trained "terrorists" - a description often used by the Ukrainian government to describe the separatists.

In rebel-held eastern Ukraine, a church service was held and residents joined a procession to a gravestone near the charred area where twisted metal and body parts came crashing down on July 17 last year.

"To the memory of the dead - 298 innocent victims of civil war," was written on the gravestone in the village of Hrabove, where a Russian Orthodox priest and an imam said prayers.

About 300 people brought flowers and flags of the victims' countries, some with black ribbons attached, and released white balloons into the sky.

Western governments believe that pro-Russian rebels shot the plane out of the sky with a Russian-supplied BUK missile. Britain and Ukraine marked the anniversary with new appeals for an international tribunal to prosecute suspects, an option also favored by Malaysia, Australia, the Netherlands and Belgium.

Russian President Vladimir Putin dismissed those calls as premature and counter-productive on Thursday and criticized "politicized" versions of the incident "planted" in foreign media.

Western diplomats say they are open to the prospect of a tribunal that is not backed by the U.N. if Russia wields its Security Council veto. (rt/ez)