The trip comes after Iraq and Saudi Arabia reopened their land border, the Arar crossing, in November for the first time in 30 years, in a new effort to revive once-frosty ties.

"The purpose of this trip is to discuss and expand ongoing cooperation and the work of the Iraqi-Saudi committee", which oversaw the re-opening of Arar, an Iraqi official told AFP.

Kadhemi's visit seeks to "further enhance economic cooperation and investment" as well as "explore ways to strengthen regional stability", the official added.

The kingdom's de facto ruler Crown Prince Mohammed bin Salman received Kadhemi at Riyadh airport.

The official Saudi Press Agency said the visit came at the invitation of King Salman.

"Today, we embark on a visit to the kingdom of Saudi Arabia to strengthen our bilateral ties and enhance regional cooperation," Kadhemi wrote on Twitter before his arrival.

"We will work on serving our peoples' interests, achieving stability and advancing developmental values based on what binds us."

Kadhemi was scheduled to travel to Saudi Arabia on his first foreign trip as prime minister last July, but the visit was cancelled at the last minute when King Salman was hospitalised for surgery to remove his gall bladder.

His trip to Tehran, Riyadh's arch-rival, went ahead, with the premier meeting Iran's supreme leader Ayatollah Ali Khamenei.

Known to maintain close personal ties with the Saudi crown prince, Kadhemi walks a diplomatic tightrope as Baghdad often finds itself caught in the tug of war between Tehran and Riyadh as well as its ally Washington.

Iraq is the second-largest producer in the OPEC oil cartel, outranked only by Saudi Arabia.

Kadhemi, whose government has sought to fast-track foreign investment including Saudi support for energy and agriculture, is pushing for deeper economic ties.

The Arar border crossing reopened to goods and people in November for the first time since Riyadh cut off its diplomatic relationship with Baghdad in 1990, following Iraqi ex-dictator Saddam Hussein's invasion of Kuwait.