NEW YORK (Reuters) - The National Football League extended its six-year television deal with NBC by another two years on Wednesday, following similar deals last spring with broadcast networks CBS and Fox.

NBC will broadcast 16 Sunday night football games in both the 2012 and 2013 seasons under the terms of the new deal, approved at an NFL meeting in Chicago. NBC also will broadcast a Thursday night game, and preseason and playoff games in both seasons.

NBC and the NFL did not release financial details of the contract extension, although sources have said in the past that the original deal was worth about $600 million each year. That deal started in 2006 and ran through the 2011 season.

The NFL signed in May extensions through the 2013 season with CBS, a unit of CBS Corp, and Fox, owned by News Corp. NBC is owned by General Electric and Vivendi.

(Reporting by Paul Thomasch; editing by Carol Bishopric)