The Japanese manufacturer, whose project is being led by four-time WRC champion Tommi Makinen, will start an extensive testing programme in March before joining the series in 2017.

Hirvonen, 35, recently made his debut in the Dakar Rally with a fourth place for the X-raid Mini squad - and the Finn will spend the rest of the season developing Toyota's WRC machinery.

He last competed in the series full-time in 2014 with M-Sport, having previously been a works driver for Ford, Subaru and Citroen, racking up 15 victories.

His former co-driver Jarmo Lehtinen has already been brought on board as sporting director.

Hirvonen replaces M-Sport's Eric Camilli as Toyota's lead tester, while the team has also employed tarmac-specialist Bryan Bouffier and former Hyundai driver Juho Hanninen in testing roles.

The Japanese marque is looking to sign an established name to lead its return to the category for the first time since 1999 - and Hirvonen would fit the bill, although it is believed the team has also approached Volkswagen drivers Sebastien Ogier and Jari-Matti Latvala.

Additional reporting by Giacomo Rauli