The pipeline, to pump 10-20 billion cubic meters of gas to Europe via Russia's pipeline network, is a rival project to a Western-backed trans-Caspian pipeline that bypasses Russia, currently the sole re-exporter of Turkmen gas.
"Under the feasibility study and design documents, we were due to start the construction in the second half of 2008, but Turkmenistan is capable of launching the project ahead of schedule," Gurbanguly Berdymukhammedov said after talks with Russia's premier, Viktor Zubkov, without giving a date.
Russia, Turkmenistan and Uzbekistan agreed to build the pipeline in May 2007 and were to finalize it in September, but have so far failed to agree on the price of supplies.
Speaking at a joint news conference, the Russian premier said they had agreed to finalize the deal in the near future and "start work shortly." Zubkov said they had reached "absolute understanding" on cooperation in the oil and gas sector.
He said the two countries also plan to step up the modernization of the 1974 Central Asia-Center gas pipeline, which runs from Turkmenistan via Kazakhstan and Uzbekistan to Russia.
During talks between prime ministers of the post-Soviet Commonwealth of Independent States (CIS) in the Turkmen capital on Thursday, Berdymukhammedov said the pipeline's capacity would be raised by 20 billion cubic meters from the current 50 billion.
Turkmenistan, the second largest gas producer after Russia among ex-Soviet states, exports gas via a Russian-controlled network of pipelines, but has been considering diversifying export routes.