Saudi King Abdullah instructed authorities in the oil-rich kingdom Thursday to take "necessary measures" to defend the country from jihadists battling the government in neighbouring Iraq.
The announcement comes days after militants from the Islamic State of Iraq and the Levant (ISIL) seized the border crossing from Iraq into Jordan, which also neighbours the kingdom, as they press an offensive in Iraq.
A statement said Abdullah ordered authorities "to take all the necessary measures to protect... the kingdom's security against actions that could be taken by terrorist or other groups."
The measures were not spelled out but decided during a security cabinet meeting chaired by the king and devoted to discussing developments in Iraq and their impact on Gulf Arab monarchies.
The meeting comes on the eve of a visit to Saudi Arabia by US Secretary of State John Kerry, who has been holding talks with regional and international players to seek ways of containing the unrest in Iraq.
On Thursday, Kerry discussed the widening crisis in Iraq, where ISIL has seized cities and towns north of Baghdad, during urgent talks with his counterparts from Saudi Arabia, Jordan and the United Arab Emirates.
A senior State Department official said Kerry would brief them on his visit to Baghdad and the autonomous Kurdistan region in northern Iraq, where he urged leaders to unite against the jihadist militants.
Sunni-ruled Saudi Arabia has accused Iraq's Shiite prime minister, Nuri al-Maliki, of fuelling the crisis by marginalising the country's Sunni Arab minority.
Maliki conceded on Thursday that political measures and military action were needed to repel the militant offensive, which is threatening to tear Iraq apart.