DAMASCUS -- Saudi King Abdullah al Saud is expected to make a rare visit to Syria this week to increase pressure on Syrian leader Bashar al Assad to loosen his alliance with Iran and strengthen Arab consensus on regional political and security issues, according to Saudi officials.

The summit would be the first trip to Damascus by the Saudi ruler since he took power in 2005. It culminates months of quiet diplomacy by the oil-rich Arab nation, U.S. and European officials who see Syria as a linchpin to curbing the influence of...