A US decision to provide Ukraine with lethal weapons will fuel the conflict in the country's east, a senior Russian diplomat says.

Key points: State Department says sending weapons is to "deter further aggression"

State Department says sending weapons is to "deter further aggression" More than 10,000 people killed during conflict since 2014

More than 10,000 people killed during conflict since 2014 US has already provided support equipment and training

US officials said on Friday that President Donald Trump's administration approved a plan to provide lethal weapons to Ukraine, including American-made Javelin anti-tank missiles.

Ukraine has long sought the weapons for its fight against Russia-backed separatists in eastern Ukraine that has killed more than 10,000 people since April 2014.

The officials describing the plan were not authorised to discuss it publicly and demanded anonymity.

The State Department, responsible for overseeing foreign military sales, would not confirm that anti-tank missiles or other lethal weapons would be sent.

But in a statement, State Department spokeswoman Heather Nauert said the US had decided to provide "enhanced defensive capabilities" to help Ukraine build its military long-term, defend its sovereignty and "deter further aggression".

"US assistance is entirely defensive in nature, and as we have always said, Ukraine is a sovereign country and has a right to defend itself," she said.

Previously, the US has provided Ukraine with support equipment and training, and has let private companies sell some small arms like rifles.

Deputy Russian Foreign Minister Grigory Karasin told the state RIA Novostin news agency the US move "raises the danger of derailing the process of peaceful settlement in the Ukraine".

A 2015 peace deal brokered by France and Germany has helped reduce the scale of fighting in eastern Ukraine, but clashes have continued and the agreement's provisions for political settlement have stalled.

German Chancellor Angela Merkel and French President Emmanuel Macron issued a joint statement urging both sides of the conflict to live up to the ceasefire arrangement, known as the Minsk agreements.

"There is no alternative to an exclusively peaceful solution to the conflict," the statement read.

Move may escalate US-Russia tensions

The latest move is likely to escalate tensions between the United States and Russia, as President Donald Trump contends with ongoing questions about whether he's too hesitant to confront the Kremlin.

Mr Trump had been considering the plan for some time after the State Department and the Pentagon signed off earlier this year. Former president Barack Obama also considered sending lethal weapons to Ukraine.

The White House's National Security Council declined to comment.

Although the portable Javelin anti-tank missiles can kill, proponents for granting them to Ukraine have long argued they are considered "defensive" because the Ukrainians would use them to defend their territory and deter the Russians, not to attack a foreign country or seize new territory.

Under law, the State Department must tell Congress of planned foreign military sales, triggering a review period in which politicians can act to stop the sale.

It is unclear whether the administration has formally notified Congress, but politicians are unlikely to try to block it given that Democrats and Republicans alike have long called on the Government to take the step.

Republican senator John McCain welcomed the small arms sale earlier this week.

Senator McCain urged Mr Trump "to authorise additional sales of defensive lethal weapons, including anti-tank munitions".

"And to fully utilise security assistance funds provided by the Congress to enable Ukraine to defend its sovereignty and territorial integrity," he said.

AP