Russia's Aeroflot to buy Boeing 777s, value $4 bln

* Signs deal for 16 aircraft over 2012-2017

* Planes have catalogue price of $4.1 billion

* Move plugs gap created by delayed 787 Dreamliner

MOSCOW, Dec 16 (Reuters) - Russia's flagship airline Aeroflot AFLT.MM said it would buy 16 new Boeing 777s over the next six years as it strives to plug the gap created by the repeatedly delayed 787 Dreamliners.

The carrier said in a statement on Thursday it had signed a preliminary agreement to take the Boeing BA.N planes over the 2012-2017 period -- prior to the receipt of a fleet of the highly anticipated Dreamliners.

Aeroflot did not disclose financial details, but the order has a catalogue price of $4.1 billion.

Aeroflot had ordered 22 Dreamliners that are now nearly three years behind delivery schedule due to labour and production problems.

The most recent test flights were halted in November after a problem with the electrical system caused a fire on one of the planes.

Aeroflot is also waiting for delayed deliveries of the smaller Superjet aircraft -- a Russian-Italian joint venture and the first passenger plane built in Russia since the fall of the Soviet Union.

Deliveries are expected until early next year.

Aeroflot said in its statement it had set up a working group with Boeing to bring about the delivery of two Dreamliners in time for the Winter Olympics in Sochi in 2014. (Reporting by Gleb Stolyarov, Writing by John Bowker; Editing by Jessica Bachman, Mike Nesbit) ($1=31.10 roubles)