Saudi Arabia on Monday beheaded a Syrian drug trafficker and a convicted murderer, taking to 100 the number of executions in the kingdom this year.

The number of executions has surged in 2015 compared with the 87 recorded for all of last year. But it is still far below the record 192 which rights group Amnesty International said took place in 1995.

Syrian Ismael al-Tawm smuggled 'a large amount of banned amphetamine pills into the kingdom', said an interior ministry statement carried by the official Saudi Press Agency.

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Highly visible: Executions in Saudia Arabia are carried out in public, mostly by beheading with a sword. The country has now executed its 100th person this year

He was beheaded in the northern region of Jawf. A separate statement said that Rami al-Khaldi was convicted of stabbing another Saudi to death and was executed in the western province of Taef.

Drug and murder convictions account for the bulk of executions in Saudi Arabia.

The Berlin-based European Saudi Organisation for Human Rights said in a report that the death penalty in the kingdom is 'often applied to powerless individuals with no government connection'.

Ali Adubisi, the group's director, has said that economic factors could be leading to a rise in drug crimes. Many are turning to the illegal business 'because they are poor', he said.

According to London-based Amnesty, use of the death penalty for other than the 'most serious crimes' -- premeditated killings -- violates international law.

Saudi judicial proceedings 'fall far short' of global norms of fairness, according to the rights watchdog.

Under the Gulf state's strict Islamic sharia legal code, drug trafficking, rape, murder, armed robbery and apostasy are all punishable by death.

Those beheaded this year include Siti Zainab, an Indonesian domestic worker convicted of murder despite concerns about her mental health, according to the Indonesian newspaper Kompas.

Protest: Lebanese human rights activists hold signs saying 'Do not kill' outside the Saudi embassy in Beirut. The conservative Islamic kingdom beat its total for the whole of 2014 with its 88th execution last month

Jakarta summoned Riyadh's ambassador over her case, a rare diplomatic incident linked to Saudi Arabia's executions, around half of which involve foreigners.

Also among this year's dead are at least eight Yemenis, 10 Pakistanis, Syrians, Jordanians, and individuals from Myanmar, the Philippines, India, Chad, Eritrea and Sudan.

Saudi Arabia ranked among the world's top five executioners in 2014, according to Amnesty.

Executions are carried out in public, mostly by beheading with a sword. A surge in executions began towards the end of the reign of King Abdullah, who died on January 23.

It accelerated this year under his successor King Salman, in what Amnesty has called an unprecedented 'macabre spike'.

Activists are unable to explain specific reasons for the surge, and officials have not commented. One activist said the death penalty is carried out only with the king's final approval.

Salman has adopted a more assertive foreign policy, and in April promoted his powerful Interior Minister Mohammed bin Nayef to be crown prince and heir to the throne.

Saudi Arabia recently advertised for eight new executioners, recruiting extra staff to carry out the increasing number of death sentences.