Oil prices rose Tuesday as unrest in Libya added to potential energy supply concerns triggered by the Ukraine-Russia crisis, analyst said.

Oil prices rose Tuesday as unrest in Libya added to potential energy supply concerns triggered by the Ukraine-Russia crisis, analyst said.

The US benchmark, West Texas Intermediate (WTI) for delivery in June, climbed 15 cents to $102.76 a barrel.

Brent North Sea crude for July also gained 15 cents to stand at $109.52 a barrel around midday in London.

"Further unrest in Libya is the main factor in the oil market at the moment," David Lennox, resource analyst at Fat Prophets, told AFP.

An elite Libyan unit joined a renegade general Monday to battle Islamists in the east as rising lawlessness in the nation's two largest cities edges it closer to civil war.

Since the toppling of dictator Moamer Gaddafi in 2011, successive Libyan governments have struggled to impose order as heavily armed former rebel brigades carve out their own fiefdoms.

The political crisis in the country comes just weeks after the resumption of oil exports following a nine-month blockade of sea terminals by rebels.

Elsewhere, Russia, Ukraine and the EU plan to meet next week for talks to resolve a gas dispute between Kiev and Moscow, European Energy Commissioner Guenther Oettinger said on Monday.

Russian energy giant Gazprom has warned Kiev it could suspend its gas deliveries on June 3 if the former Soviet republic does not settle by then its bill for June, worth $1.66 billion (1.21 billion euros).

Moscow has started demanding pre-payments for gas shipments to Ukraine under new rules introduced in response to the Ukraine crisis.

This threat has raised concern in the European Union, which imports a quarter of its gas from Russia, nearly half of which flows via Ukraine.