Russia is halting development of a next-generation rocket to launch humans into space, the head of Roscosmos told Russian lawmakers in a speech Friday.

The Rus-M rocket, a liquid-fueled rocket designed to launch from Russian territory, was supposed to begin flying as soon as 2015, according to earlier statements by Russian prime minister Vladimir Putin.

"We have come to the conclusion that we do not need a new rocket, we can continue using those we already have," said Vladimir Popovkin, head of Russia's space agency, according to the Novosti news agency.

The news reports didn't indicate whether the suspension was permanent or temporary.

Popovkin was speaking to the Russian Duma, the federal government's legislative body.

The Rus-M was designed to replace the Soyuz rocket, the venerable workhorse of Russia's space program whose derivatives have launched more than 1,700 times since the dawn of the space age.

The Soyuz rocket is currently one of two rockets capable of launching humans into orbit. The other is China's Long March 2F booster.

The two-stage Rus-M vehicle was supposed to ultimately launch from the Vostochny Cosmodrome, a planned space center in Russia's Far East just north of the border with China. Located in Russia's Amur region, Vostochny is envisioned as a replacement for the Baikonur Cosmodrome, Russia's primary launch site that was left on Kazakhstan territory after the collapse of the Soviet Union.

Russia now rents Baikonur from the Kazakh government for $115 million per year. The rental agreement is the subject of some discord in the relationship between Moscow and Astana.

Vostochny was conceived as a way to reduce the Russian reliance on Baikonur, which hosts manned space missions and launches of commercial communications satellites. Vostochny lies at almost the same latitude as Baikonur, so rockets could provide similar performance there while launching capsules to the International Space Station or lofting communications payloads.

Russia's other major launch site is the Plesetsk Cosmodrome, a military facility in far northern Russia. It is tailored for satellites bound for polar orbit.

Vostochny's development has been delayed for several years, and construction is now not expected to begin until 2012.

The Rus-M was expected to be the core element of Russia's future space infrastructure, launching a next-generation piloted capsule and a range of satellites into orbit. It was designed to come in several configurations for different types of missions, with its first stage powered by multiple kerosene-fueled RD-180 engines and a hydrogen-fueled upper stage.

The overall preliminary design contract for the Rus-M was awarded to TsSKB-Progress, the state-controlled production center that also builds Soyuz rockets.