RIYADH (AFP) - A group of Saudi activists has called in a petition for a sweeping reform of political institutions that would reduce the royal familys role and move the kingdom towards a constitutional monarchy. In a petition sent to King Abdullah and other leaders, obtained by AFP on Friday, the 77 rights activists and lawyers called for the creation of an elected parliament and for a non-royal prime minister to run the government. The letter fell short of demanding a constitutional monarchy, calls for which in 2003-2004 led to the arrest of activists. Saudi Arabia needs a balance of authority and power between different institutions similar to .. what is being implemented in some other constructional monarchies like UK (Britain), Jordan, and Morocco, they said. Constructional monarchy is a seldom-used term for a monarchy in which the sovereign is the head of state but the government is led by a prime minister. In the Saudi absolute monarchy, King Abdullah is prime minister while his half-brothers Crown Prince Sultan bin Abdul Aziz and Prince Nayef bin Abdul Aziz are deputy premiers. We demand that the prime minister should be a commoner to ease accountability and to manifest the principle of circulations of authority, they said. They added a call for limiting the terms of appointed royal family members in govt posts. The calls for political reform came as part of a letter dated Wednesday criticising the opening of secret tribunals for nearly 1,000 militants, mostly arrested in the wake of a 2003-05 Qaeda linked campaign of attacks. The activists also called for separating the currently closely-entwined executive, judicial and legislative branches of govt. A legislative Shura council is wholly appointed by the king and has few powers to check other institutions, though King Abdullah has increasingly allowed it to investigate the policies and operations of various ministries. The signatories stressed the call to hold polls, especially for parliament. Saudi Arabia held its first election in recent memory in 2005, for 178 municipal councils. A new round was expected this year but until now no announcement has been made. It will be in the best interest of the monarchy if the public is allowed to participate in the election process and is given a choice, and a voice. This in turn will lead to healthy competition and will allow democracy to prevail, they said. The activists also recommended that an elected parliament have a role in deciding the succession to the throne. Current rules say succession will be decided by the king and the Allegiance Commission, a body of high princes established in 2006 to help decide the next heir to the throne. On the trials of 991 alleged militants, the activists said they were taking place in secret ad hoc security courts and they questioned any verdicts reached away from public scrutiny. We are calling for fair and public trials, otherwise it is impossible to mete out justice, they wrote. The secrecy of the trials, they argued in the petition, will grant the government carte blanche to pass tough verdicts against helpless and powerless defendants. The government has neither confirmed nor denied that the trials have actually started.