Saudi authorities on Tuesday beheaded a Syrian convicted of drugs trafficking, the interior ministry said, in the third execution this year in the ultra-conservative kingdom.

Mohammed al-Mahameed was caught smuggling a significant amount of amphetamines, the ministry said in a statement carried by the SPA state news agency.

Three Saudi guards including a top commander were killed on Monday in a rare attack and suicide bombing by "terrorists" on the kingdom's border with Iraq, the interior ministry said.

Four attackers were also killed in the clash, two in suicide blasts.

Saudi Arabia announced on Saturday it was sending a delegation to Iraq ahead of opening an embassy in Baghdad where its last mission closed nearly 25 years ago.

A foreign ministry statement said the delegation would "take the necessary decisions to choose and equip buildings" for an embassy in Baghdad and a consulate in Arbil, capital of the autonomous Kurdistan region in the north.

Saudi King Abdullah, hospitalized earlier this week, is suffering from pneumonia and breathing with the aid of a tube, but is in stable condition, the royal court said on Friday.

The long-ailing king, who is believed to be around 90 years old, was admitted to the King Abdul Aziz Medical City in Riyadh on Wednesday for checks.

Saudi police have arrested a man wanted in connection with a 2011 protest movement organised by Shiite residents of the kingdom's restive Eastern Province, the interior ministry said Friday.

Muntadher Ali Saleh al-Sabity was detained on Thursday evening in an operation in the town of Awamiya, the official SPA news agency quoted a ministry spokesman as saying.

A Saudi convicted of drug trafficking became the first person executed in 2015 in the ultra-conservative Muslim kingdom which beheaded 87 people last year, according to an Agence France Presse tally.

Malik bin Said al-Sayaari was put to the sword in the Al-Hasa district of Eastern Province after a repeat conviction for hashish smuggling, the interior ministry said.

Saudi Arabia on Thursday beheaded a Pakistani man for heroin smuggling, the 13th prisoner from Pakistan to be executed in the kingdom for drug trafficking since mid-October.

His beheading in the western Mecca province brings to 87 the number of Saudis and foreigners executed this year in the oil-flush state, according to an Agence France Presse tally.

Saudi Arabia's ailing King Abdullah was admitted to hospital on Wednesday for "medical checks," the royal court said, with the country's stock market falling sharply following the news.

The king, whose age and frequent hospitalization have raised concerns about the future leadership of the key oil producer, was admitted to the King Abdulaziz Medical City in Riyadh, a court statement carried by the official SPA news agency said.

Saudi Arabia beheaded Monday a man for stabbing to death a relative, the interior ministry said.

Misfir bin Nasser bin Misfir Lesloom al-Yami was found guilty of killing Hamad bin Ali bin Hamad Lesloom al-Yami following a fight, the ministry said in a statement carried by SPA state news agency.

Head of the Kataeb party Amin Gemayel is expected to pay Saudi Arabia a visit upon the invitation of deputy Crown Prince Muqrin bin Abdul Aziz, media reports reported on Saturday.

Gemayel received a phone call from the Crown Prince who congratulated him on the holidays and invited him to visit the kingdom.