DUBAI, March 12 (Reuters) - Death sentences against four Saudi men convicted of terrorism have been confirmed by 13 judges, a Saudi newspaper reported, raising the possibility of a new round of executions two months after 47 people including a prominent Shi'ite cleric were put to death.

International rights groups said the families of three young Shi'ite Muslim men feared their sons, arrested for involvement in anti-government protests while under the age of 18, were among those facing the death penalty. One is a nephew of Sheikh Nimr al-Nimr, the cleric whose execution in January led to a rupture of diplomatic relations between Saudi Arabia and Iran.

Officials from the Saudi justice ministry and the interior ministry were not immediately available to comment.

Saudi newspaper Okaz said: "The four terrorists awaiting the implementation of the death sentences complement the first group of 47." It said a total of 13 judges had considered the cases in three levels of hearings, but did not identify the four men.

Rights group Reprieve, which campaigns against the death penalty, said: "While details of the four in line for execution remain unclear, the reports will raise fears for three juveniles who are awaiting execution after their sentences ... were upheld in the SCC (Specialised Criminal Court) last year."

The three are Dawoud al-Marhoon, arrested in 2012; Abdullah Hassan al-Zaher, who was 15 when he was arrested in 2011; and Ali al-Nimr, aged 17 when he was detained in 2012. France has called on Saudi Arabia not to execute Nimr, arguing he was a minor at the time.

Amnesty International said: "If these executions go ahead, Saudi Arabia will demonstrate its utter disdain for international law, which prohibits executions of people for crimes committed under the age of 18."

In November last year, two Saudi newspapers reported that Saudi Arabia was planning to execute more than 50 people for "terrorist crimes" that killed more than 100 civilians and 71 security personnel. urn:newsml:reuters.com:*:nL8N13I4CD

The 47 executed on Jan. 2 were mostly Sunnis convicted of al Qaeda attacks in the kingdom a decade ago. Four, including the older Nimr, were members of the Shi'ite minority who were accused of involvement in shooting policemen. urn:newsml:reuters.com:*:nL8N14M08M

Nimr's execution sparked demonstrations in eastern Saudi Arabia and in Shi'ite Iran, where angry crowds ransacked the Saudi embassy in Tehran, prompting Riyadh to break off ties with Iran.

(Reporting by Sami Aboudi, Editing by Mark Trevelyan) ((sami.aboudi@thomsonreuters.com; Tel: +971-4-3918301))

Keywords: SAUDI SECURITY/EXECUTIONS