DONETSK (Reuters) - Xabi Alonso marked his 100th Spain appearance by scoring both goals as the holders eased to a comfortable 2-0 win over a feeble France on Saturday and into a Euro 2012 semi-final against Portugal back in Donetsk on Wednesday.

France coach Laurent Blanc's tactics of playing two right backs in a defensive lineup backfired as impressive Spanish left back Jordi Alba skipped through to the byline after 19 minutes and picked out an unmarked Alonso, who headed firmly home.

Alonso added his second from the penalty spot in added time after Pedro was tripped by Anthony Reveillere to wrap up Spain's first competitive victory over their neighbors.

France, who had won five and drawn one of the teams' six previous competitive meetings, were spectators for long spells as Spain played their usual, mesmerizing possession game without taking any risks in search of a second goal.

The French livened up marginally after the break with Mathieu Debuchy heading just over but they failed to seriously test Spain keeper Iker Casillas during a match high on technical ability but short on drama, atmosphere and goalmouth action.

(Writing by Mitch Phillips, editing by Ken Ferris)