UPDATE 4-Nord Stream pipeline gets nod from Sweden, Finland

* Sweden, Finland govts approve pipelines in their waters

* Finnish environmental decision due by year-end

* Russia PM Putin thanks Finland, Sweden

(Adds comments from analyst and Polish official, background) By Simon Johnson

STOCKHOLM, Nov 5 (Reuters) - A plan by Russian-German consortium Nord Stream to build a gas pipeline under the Baltic Sea cleared two major hurdles on Thursday as Sweden and Finland signed off on construction in their waters.

Nord Stream has raised fears both among environmental groups, who are worried about the impact on the Baltic Sea, and countries such as Poland, Ukraine and the Baltic states which view the project as a threat to their energy security.

"The basic risk is that once it becomes operational Russia could stop deliveries to Poland without affecting its key client, that is Germany," said Przemyslaw Wipler, a former top oil expert in the Polish government.

European Union officials have backed the pipeline because it means the bloc, while still heavily dependent on Russia for energy needs, would be less at risk of supply disruptions due to Moscow's running dispute with Kiev.