MADRID (Reuters) - Spain's new immigration rules will allow for the regularisation of some 300,000 undocumented migrants per year over the next three years as the country seeks to expand its labour force, Migration Minister Elma Saiz told reporters on Tuesday.

Unlike many of its European peers - such as Italy - Spain, led by a leftist minority coalition government, has been largely receptive to migrants.

"Spain has to opt between being an open, prosperous country or being a closed and poor one, and we have chosen the former," Saiz said, adding that the nation needs around 250,000 to 300,000 foreign workers a year "to sustain (its) welfare state".

The reform shortens and simplifies legal and administrative procedures for work and residence permits, allowing migrants to register as self-employed as well as employees, and provides them with additional labour rights guarantees.

(Reporting by Inti Landauro; Writing by David Latona; Editing by Andrei Khalip)