Daimler and Nissan have finalized a joint venture deal to build future Mercedes and Infiniti compact cars in Mexico, sources with knowledge of the matter said on Thursday as the automakers called a news conference to unveil the plans.

The companies are preparing to announce an investment to develop the vehicles on Daimler's front wheel-drive architecture and assemble them at Nissan's Aguascalientes site northeast of Guadalajara, the sources said.

The 50-50 venture, first reported by Reuters in March, will broaden Nissan's premium Infiniti lineup, expand Daimler's North American production and reinforce the German carmaker's relationship with the Renault-Nissan alliance.

Daimler Chief Executive Dieter Zetsche and his Renault-Nissan counterpart Carlos Ghosn will unveil a new cooperation deal at a news conference on Friday, both companies said, declining to comment further. A separate news conference is to be held in Mexico.

The new manufacturing deal will be the "largest project in the global collaboration of Daimler and the Renault-Nissan Alliance," Daimler said.

Mercedes, Nissan and alliance partner Renault have shared engines, plants and vehicle architectures for small cars and vans since Zetsche and Ghosn announced a partnership in 2010, underpinned by small reciprocal shareholdings.

The compact car plans, set out in a February memorandum of understanding, will help Infiniti fill a gap at the bottom end of its range with a new SUV, sedan and coupe sharing parts and architecture with successors to the Mercedes A- and B-Class, GLA and CLA, sources have said.

In return, Daimler gets a first North American production line for its "MFA" vehicle architecture, as well as development savings and economies of scale - in a vehicle category where it has struggled in the past with low profitability.