Speaking after talks with visiting President Islam Karimov, President Vladimir Putin said: "Both sides reaffirmed their interest in implementing agreements to swiftly modernize the natural gas transportation infrastructure in the Central Asian region."

"We look to proactive cooperation with Kazakhstan and Turkmenistan in their implementation," Putin said.

The four former Soviet allies agreed in May to modernize the 1974 pipeline, which runs from Turkmenistan via Kazakhstan and Uzbekistan to Russia, in a bid to raise its capacity by 20 billion cubic meters from the current 50 billion per day.

Turkmen President Gurbanguly Berdymukhammedov earlier said the pipeline would eventually pump 230 million cubic meters of gas per day, RIA Novosti reported.