ATHENS (Reuters) - The International Olympic Committee on Tuesday approved all venue sites for the 2014 Winter Games in Russia's Black Sea resort of Sochi.

Organizers were forced to relocate some of the sports because of environmental concerns, raising questions over construction deadlines.

"With the approval of biathlon, the IOC today finalized the venue locations... following the decision taken earlier this year to relocate some of the sites because of environmental considerations," the IOC said in a statement.

It said Sochi Games organizers could now move ahead with the planning and construction of the venues, the majority of which need to be built from scratch.

Sochi was awarded the Games last year but delayed the construction of some proposed sites after environmental groups said they would affect nature reserves in the Krasnaya Polyana mountains.

"The new locations for these venues don't just provide the athletes with the best possible facilities, they will also ensure that any environmental impact is kept to a minimum," IOC inspector Jean-Claude Killy said.

Russian Prime Minister Vladimir Putin, who personally lobbied for the Games to be given to Russia, urged organizers last month to speed up preparations saying any delays would be "inadmissible."

"All construction work will be completed according to schedule," Games chief Dmitry Chernyshenko said on Tuesday.

"In fact, construction work in several venues within the mountain cluster is ahead of schedule, and construction in the Immeretinskaya Valley will start soon," he said.

(Reporting by Karolos Grohmann, editing by Rex Gowar)