Iker Casillas has extended his stay at Porto for another season.

Former Real Madrid goalkeeper Casillas was out of contract with Porto, but announced his new deal on Thursday.

He wrote on Twitter: "Very happy to continue for one more season with Porto! Looking forward to the challenges that arise!" 

The 36-year-old has spent the last two seasons with Porto after leaving Real Madrid, where he played his whole professional career until 2015.

He initially signed a two-year contract that contained the option for a third year, although the extra year was reportedly subject to negotiation over finances.

Casillas played 65 Primeira Liga games across the last two campaigns, in which Porto finished third and then second, with Benfica winning the title on each occasion.

Benfica have won the league for four consecutive seasons, with Casillas yet to win a trophy since his move.