BISHKEK: Kyrgyzstan on Thursday accused Uzbekistan of building up its military presence at their shared border in retaliation for Kyrgyzstan's attempt to reclaim a water reservoir at a contested spot.

Tensions flared up at the border between the two Central Asian nations last week when Uzbekistan closed one border crossing and moved troops and vehicles to the contested part of the border. Kyrgyzstan responded by imposing restrictions on border crossing from their side. The two countries have since exchanged several diplomatic notes and the Kyrgyz president on Thursday said he may boycott a regional security conference in Uzbekistan's capital in June because of the ongoing spat.

The two former Soviet republics are estimated to have over 300 kilometers (190 miles) of border that has not been demarcated.

Kurbanbay Iskanderov, a Kyrgyz government envoy for border demarcation, told reporters Thursday the tensions were triggered by the government's decision to reclaim its control over Kyrgyz facilities in Uzbek use, including the reservoir 10 kilometres (6 miles) from the border.

Iskanderov said the Uzbek military were called to the border a few days after Kyrgyzstan denied Uzbek workers access to the reservoir in Ala-Buka.

"There are disputed portions on the Kyrgyz-Uzbek border that should be Kyrgyz but they are used by Uzbekistan," Iskanderov said.

Uzbekistan has rejected accusations of a disproportionate military buildup, saying that it was merely tightening security checks at the border ahead of the celebrations of Nowruz, the Persian New Year that is observed in both countries.

Tensions abated on Monday when Uzbekistan and Kyrgyzstan agreed to cut the number of troops at one border crossing to eight each.

The simmering border dispute is aggravated by the fact that the two nations, once part of the Russian Empire and the Soviet Union, never shared a border as sovereign states in the 20th century before both declared independence in 1991. Experts on both side disagree which Soviet maps should be used for demarcation since the frontier between the Soviet republics had been adjusted several time during Communist rule.

Kyrgyzstan is home to a sizeable Uzbek minority, and ethnic tensions have simmered there for years. In 2010, at least 400 people were killed and thousands injured in riots in the Kyrgyz city of Osh.