Los Angeles, June 28 (IANS): As "Star Trek 3" began production in Vancouver, Canada, last week, Paramount Pictures, the studio behind the "Star Trek" franchise, has reportedly signed two lead stars for a potential fourth installment.

Actors Chris Pine and Zachary Quinto, who play Captain Kirk and Mr. Spock respectively, have been granted an option for "Star Trek 4" as the studio renegotiated their deals.

According to sources, the studio "recently completed last-minute re-negotiations with (Pine and Quinto), a move that has added as much as $10 million to $15 million to the budget", reports hollywoodreporter.com.

Pine, who earned $600,000 in 2009's "Star Trek", $1.5 million for "Star Trek Into Darkness" and $3 million for "Star Trek 3", reportedly scored $6 million for the fourth movie.

Paramount is said to have ultimately made some concessions to the original "Star Trek" actors including Chris, Zachary, Zoe Saldana, Simon Pegg, Karl Urban, Anton Yelchin and John Cho as the actors are getting more successful and more expensive. The studio originally wanted to give nominal raises to the actors based on their 2007 contract, but their representatives argued that seven years had passed since then.

Under California law, a personal services contract cannot bind someone for more than seven years. That meant the cast's original deals were arguably invalid as of 2014.