“I know it can take time. From our point of view it should take all the time required,” said Bildt during a visit to Poland.
Warsaw has also expressed concern at the environmental impact of the planned pipeline, which would link Russia and Germany and is scheduled to be running by 2010.
Sweden, Finland and Denmark, through whose waters the pipeline is expected
to pass, feel strong “environmental responsibilites” for the Baltic, said Bildt.
Asked when Sweden and its neighbours would make a decision on the pipeline, Bildt said: “It really depends to what extent the consortium can answer the different (environmental) questions.”
Russian gas giant Gazprom and German firms BASF and E.ON agreed in 2005 to build a 1,200-kilometre (740-mile) pipeline beneath the Baltic Sea to carry Russian natural gas to Germany.
On Friday the Swedish Environmental Protection Agency urged Nord Stream, a subsidiary of Gazprom, to carry out comprehensive tests on the planned route’s impact on marine wildlife.
The same day, Latvia also called for a probing study into the environmental impact of the pipeline, in particular to allay fears it might disturb chemical weapons dumped in the Baltic by the Soviet Union after World War II.
Nord Stream is due to deliver its environmental impact report and the route for the pipleline in the autumn.
Earlier this month, former German chancellor Gerhard Schroeder, now the head of Nord Stream, said there was little possibility of the pipeline damaging the Baltic environment.
He oversaw the signing of the pipeline deal shortly before leaving office in September 2005. Amid some controversy, he subsequently took up the job with Nord Stream.
Gazprom has also said the pipeline is ecologically sound.