"Ukraine is a superb transit country and raising the question of bypassing it by some alternative gas pipelines is a crazy idea," Tymoshenko told the 45th Munich Security Conference.
Europe has renewed interest in diversifying its gas imports since a dispute between Russia and Ukraine in January left around 20 countries short of gas. Deliveries via Ukraine resumed on January 20.
"I would like to stress once again - Ukraine did not begin the [gas] crisis, but settled it," Tymoshenko said.
Tymoshenko also called on Russia to join Ukraine in "constructive, mutually acceptable avenues of cooperation."
There are currently several projects of alternative gas supply routes to Europe.
The Nord Stream pipeline, which will pump gas from Siberia to Europe under the Baltic Sea, bypassing East European transit countries, is being built jointly by Gazprom, Germany's E.ON and BASF, and Dutch gas transportation firm Gasunie at an estimated cost of $12 billion.
The South Stream pipeline is designed to annually pump 31 billion cubic meters of Central Asian and Russian gas to the Balkans and on to other European countries, but its capacity could be increased by a further 16 billion cu m. The project involves Bulgaria, Serbia, Hungary, Italy and Greece.
The Nabucco pipeline is viewed as a rival to the South Stream project and is designed to link energy-rich Central Asia to Europe through Turkey, Bulgaria, Romania, Hungary and Austria, bypassing Russia and Ukraine.
