Jonas Valanciunas has agreed to a four-year contract extension with the Toronto Raptors, the NBA franchise announced on Thursday.

The Raptors did not disclose the financial details of the deal, but Valanciunas, 23, is reportedly set to earn $64million with a player option to return to free agency entering the fourth year.

Valanciunas, who was eligible to become a free agent at the end of the 2015-16 season, averaged a career-best 12 points, 8.7 rebounds and 1.2 blocks per game last term.

"Jonas' contributions continue to improve with each season and we view him as a significant part of what we are building in Toronto," said Raptors general manager Masai Ujiri in a statement.

The Lithuanian star was the fifth overall pick by the Raptors in 2011, but his first season in the NBA was during the 2012-13 campaign.

Valanciunas joins Anthony Davis (New Orleans Pelicans) and Damian Lillard (Portland Trail Blazers) as part of the 2012-13 rookies to receive extensions.