(Updates with European Commission comment, paras 9-11)
BERLIN, Jan 29 (Reuters) - German Chancellor Angela Merkel has called on all EU members to give their full backing to the planned Nord Stream gas pipeline which is opposed by Baltic states and Poland. In a letter seen by Reuters, Merkel told European Commission President Jose Manuel Barroso and Czech Prime Minister Mirek Topolanek the gas crisis with Russia had shown "the European Union must be more independent and crisis-resistant".
The letter to the two leaders appeared to be an attack on comments by Topolanek, who holds the EU's rotating presidency.
This week, he said Russia's plans to build the Nord Stream and South Stream pipelines threatened Europe's Nabucco project, an alternative route to bring gas from Central Asia and the Caspian to western Europe, bypassing both Russia and Ukraine.
In her letter, however, Merkel backed the Nabucco project as well as Nord Stream, also known as the Baltic pipeline, and the South Stream plans.
"It is very important that these projects are politically desired and supported by all EU nations," Merkel wrote.
She also said the 27-member bloc needed to have a coordinated approach to be as effective as possible.
"We should have an intensive discussion at our spring summit on how to ensure that Europe speaks more strongly with one voice in its dialogue with producers, transit countries and consuming nations," she wrote.
Commenting on Merkel's letter, the European Commission said it supported the Nord Stream and Nabucco projects and was neutral on South Stream.
"Nabucco is the priority number one in our diversification policy," Commission spokesman Ferran Tarradellas Espuny told a daily news briefing.
"As for the Nord Stream, it has been defined as a priority by the EU. The Commission is in favour of developing that project, provided that environmental rules are respected."
EU efforts to reduce its dependence on Russian gas have been spurred on by this month's gas row between Russia and Ukraine, which disrupted supplies to other European countries.
The Nord Stream pipeline, agreed by former German Chancellor Gerhard Schroeder and Vladimir Putin, who was then Russian president, has been a source of tension between Berlin and Warsaw and the Baltic states.
It would run through the Baltic Sea directly to Germany, bypassing states like Poland to the east.
South Stream is a proposed pipeline that could be a supply route to southern Europe via the Balkans bypassing Ukraine.
Merkel also said in the letter it would be important for the EU to agree energy issues with Russia as part of a partnership and cooperation agreement.
(Additional reporting by Marcin Grajewski in Brussels) (Writing by Madeline Chambers)