"OAO Gazprom paid the first stake ahead of schedule," BELTA said, citing a statement by the government property management agency. "The $625 million ... will go to the republican national development fund."
Belarus said the shares would be transferred to Gazprom on June 15.
The May 18 deal to buy 50% in Beltransgaz for $2.5 million in four equal installments till 2010, acquiring a 12.5% stake in Beltransgaz at each stage, is expected to tighten Gazprom's operational control of the Yamal-Europe pipeline, so far its main export route to Central Europe running through Belarus.
The Russian energy giant said earlier that the Belarusian pipeline was worth $3.3 billion, well below the $5 billion valuation Belarus had long insisted on. The final deal was largely concluded late last year as Russia and Belarus became embroiled in an oil and gas dispute after Gazprom, keen to bring former Soviet republics in line with market rates for energy supplies, doubled the gas price to $100 per 1,000 cubic meters.