Azerbaijan has temporarily closed its checkpoint at the only road linking Armenia with the disputed region of Karabakh and accused the Armenian branch of the Red Cross of smuggling, according to the Azerbaijani state border service on Tuesday.

The Armenian-populated region has been at the center of a decadeslong territorial dispute between the Caucasus archfoes, which have fought several wars over the mountainous territory.

"The passage through Lachin checkpoint of the state border is temporarily suspended" pending an investigation into the Red Cross using its medical vehicles for "smuggling," Azerbaijan’s state border service said.

Azerbaijan in April set up the border point at the entrance to the Lachin corridor, exacerbating allegations from Armenia of a Karabakh "blockade." Tensions soaring over the move left another half a dozen people killed from both sides since December.

Baku fervently denied the claims, saying the checkpoint was created in response to security threats from Armenia and citing the transfer of weapons and ammunition to the Karabakh region.

In late June, the Armenian branch of the Red Cross said that Azerbaijan was blocking access to Karabakh as concern grew over the humanitarian situation in the restive region.

Azerbaijan’s state border service said several days later that traffic through the Lachin corridor – policed by Russian peacekeepers – resumed on June 26.

The latest developments followed a months-long protest by Azerbaijani environmental activists, which Yerevan claims spurred a humanitarian crisis and food and fuel shortages.

Azerbaijan insisted at the time that civilian transport could go unimpeded through the Lachin corridor.

In February, the International Court of Justice (ICJ) – the U.N.’s top judicial body – had ordered Azerbaijan to ensure free movement on the road.

The two former Soviet republics fought two wars to control Karabakh in the 1990s and again in 2020.

Six weeks of fighting in autumn 2020 ended with a Russian-sponsored cease-fire that saw Armenia cede swathes of territories it had controlled for decades.

There have been frequent clashes at the two countries' shared border despite the ongoing peace talks between Baku and Yerevan under mediation from the European Union and the United States.

When the Soviet Union collapsed in 1991, ethnic Armenian separatists in Karabakh broke away from Azerbaijan. The ensuing conflict claimed some 30,000 lives.

With major regional power Russia struggling to maintain its decisive influence because of the fallout from its war on Ukraine, the conflict has also drawn Western mediation efforts. Washington has been sponsoring peace talks, hosting ministers from both sides to hammer out an agreement twice this year alone, while the European Union has been mediating at the level of leaders between the former Soviet republics.

Baku and Yerevan say "tangible progress" was made at these talks but emphasize "more work" is needed.