The US raised its level of alert in Saudi Arabia earlier this month

It has also advised American citizens in the country to consider leaving.

The US Government "continues to receive indications of terrorist threats aimed at American and Western interests", the State Department said.

Threats included the targeting of civil aviation and other transport, its statement added.

Earlier this month, the US put its diplomats in Saudi Arabia on a heightened state of alert due to security concerns there.

Last month, 18 people died when suicide bombers targeted a foreign workers' compound in the city.

Spate of warnings

The State Department said American citizens in Saudi Arabia "should remain vigilant, particularly in public places associated with the Western community".

"Credible information indicates that terrorists continue to target residential compounds in Saudi Arabia, particularly in the Riyadh area, but also compounds throughout the country," it said.

Militants have attacked residential compounds in Riyadh

The statement also warned Americans against travelling to the desert kingdom.

It did not say whether the latest advisory was prompted by a specific new threat or the ongoing alert.

There has been a rash of warnings by the State Department to Americans in Saudi Arabia, or planning to travel there, over the past few weeks.

In November, the US closed its embassy and consulates in Saudi Arabia for a week because of a terror threat, while earlier this month diplomats were ordered not to leave their quarters unnecessarily.

Militants have targeted residential compounds in Saudi Arabia over the past few months.

On 8 November, car bombers struck al-Muhaya compound in western Riyadh, killing 17 people, and wounding more than 120.

On 12 May, eight Americans were among 35 people killed in a triple suicide bombing at residential compounds in the capital.