LONDON, Sept 7 (Reuters) – Armenia and Azerbaijan accused each other on Thursday of moving troops close to their joint border as tensions over the future of the Nagorno-Karabakh enclave rose even as the two countries said they remained committed to a peace process.

Nagorno-Karabakh, an ethnic Armenian enclave internationally recognised as part of Azerbaijan but run by ethnic Armenian authorities, is at the centre of a rancorous standoff, with Azerbaijan restricting movement along the only road to it from Armenia to thwart what it says is arms smuggling.

Armenian Prime Minister Nikol Pashinyan on Thursday accused Azerbaijan of conducting an "ongoing military build-up along the line of contact in Nagorno-Karabakh and the Armenia-Azerbaijan border", according to Armenian state news agency Armenpress.

Armenia's foreign ministry, which said Yerevan was not interested in military escalation and was ready to continue efforts to secure a peace deal, said the information had been confirmed by various sources.

Azerbaijan's foreign ministry rejected the Armenian assertion in a statement which called on Yerevan to end what Baku called "military and political provocations."

"These claims are…part of another fraudulent political manipulation," the foreign ministry said.

Hikmet Hajiyev, foreign policy adviser to Azerbaijan's President Ilham Aliyev, told Reuters that Azerbaijan's armed forces were conducting pre-planned drills in preparation for the autumn and winter.

"It's part of the regular planning process," said Hajiyev, accusing Armenia in turn of concentrating troops on the border and of purchasing new weaponry systems.

He said ethnic Armenian forces inside Nagorno-Karabakh had also come out of their regular barracks and deployed to front line positions in what he said was a high level of alertness.

Armenia did not comment on its own troop movements.

"Our strategy is about deterrence and deterring any armed or illegal military actions or provocations against Azerbaijan," said Hajiyev.

Russia, which has maintained peacekeepers in the region since a 2020 war in which Azerbaijan seized back significant amounts of territory it had lost to Armenian forces in the 1990s, said on Thursday it was continuing to fulfil its role as a security guarantor in the South Caucasus.

Kremlin spokesman Dmitry Peskov criticised Armenia's decision to host a joint exercise involving 85 U.S. soldiers next week as unhelpful however.

"In this situation, holding such exercises does not contribute to stabilising the situation in any case and strengthening the atmosphere of mutual trust in the region," Peskov said.

"But Russia continues to fulfil its functions as a guarantor of security, Russia continues scrupulous, consistent and constructive work with both Yerevan and Baku."