HELSINKI, March 2 (Reuters) - Finland and Sweden voiced concern on Friday about the potential environmental impact of a gas pipeline under the sea from Russia to Germany.

"You want to be absolutely sure about all the environmental aspects the pipeline would have," Finnish Environment Minister Stefan Wallin told Reuters after meeting his Swedish counterpart, Andreas Carlgren, on Friday.

"The topography of the bottom of the sea will have to be as flat as possible ... you have to be absolutely sure where the corridor for the pipeline is."

The 5-billion-euro ($6.6 billion) pipeline would run 1,200 km (746 miles) from Vyborg in Russia to Greifswald in Germany.

"We have to underline that we really want good quality environmental impact assessments on the pipe," Carlgren said. "You could expect effects from the gas pipeline."

The pipe's builder Nord Stream, majority-owned by Russian gas giant Gazprom <GAZP.MM>, is drafting an assessment plan.

Finland's Environment Ministry said this week that Nord Stream had not offered environmental justifications for the proposed routing or alternatives to it, and information on the state of the seabed so far was insufficient.

"They should describe and compare that with other possible ways to build it or other geographical alternatives for the pipeline," Sweden's Carlgren said.

Sweden's Environmental Protection Agency said last month it wanted an evaluation of alternative routes across the Baltic and of the consequences of not undertaking the project at all.

Lithuania's Environment Ministry has said alternatives to the pipeline should be discussed, including one that would be overland, because weapons left on the seabed since World War Two could cause an ecological catastrophe if they were disturbed.

Latvia, Lithuania, Estonia and Poland worry the pipeline could allow Russia to turn off transit pipes across their territory which guarantee their energy supplies.

AlertNet news is provided by