VIENNA, May 17 (Reuters) - Saudi Arabia's foreign minister said on Tuesday that if Syrian President Bashar al-Assad did not abide with efforts to establish a truce across Syria country, alternatives would need to be looked at.

"We believe we should have moved to a 'Plan B' a long time ago," Adel al-Jubeir told reporters after a meeting of foreign governments in Vienna.

"The choice about moving to an alternative plan, the choice about intensifying the military support (to the opposition) is entirely with the Bashar regime. If they do not respond to the treaties of the international community...then we will have to see what else can be done."

(Reporting By Shadia Nasralla; writing by John Irish) ((john.irish@thomsonreuters.com; 0033-1 49 49 53 42; Reuters Messaging: john.irish.thomsonreuters.com@reuters.net))

Keywords: MIDEAST CRISIS/SYRIA SAUDI