Ukraine's president is courting European support against what he says are 9,000 Russian troops occupying 7 percent of his nation's territory.

Addressing the World Economic Forum in Davos on Wednesday, President Petro Poroshenko held up a piece of a bullet-riddled bus as evidence of shelling last week by Russian heavy artillery in "occupied" parts of his country.

The Ukrainian leader called the scrap of yellow metal — a relic of Volnovakha, the town where 13 people were killed when a bus was shelled — a "symbol of the terroristic attack against my country" and evidence of Russia's hand in the conflict.

Russia, Ukrainian, French and German diplomats were converging on Berlin later for talks on a recent escalation of fighting between Ukrainian government forces and Russian-backed separatists.