Marquez has been waiting several months for the call to swear allegiance to the Spanish Constitution. He will then be eligible to appear for Barcelona as a European Union player.

Marquez's citizenship would free up a place in Barcelona's squad for a non-EU player, with reports suggesting it will go to another Mexican, 17-year-old playmaker Giovani dos Santos, who plays for the reserve team.

Dos Santos, who helped Mexico win the under-17 World Cup last year, is currently excluded from appearing for Barcelona's first team by rules which allow Spanish clubs only three non-EU players in their squads. Marquez, Ronaldinho and Samuel Eto'o currently make up Barcelona's quota.

Marquez, 27, has helped Barcelona win the Champions League and two Spanish league titles since joining from AS Monaco in 2003.

Barcelona leads the Spanish league with 23 points from 10 games.