(Recasts after meeting)
BEIRUT, Aug 27 (Reuters) - The Lebanese Shi'ite Muslim group Hezbollah and allied Christian politicians boycotted a cabinet meeting on Thursday, a sign of rising political tensions that have paralysed Prime Minister Tammam Salam's national unity government.
Ministers from the Free Patriotic Movement (FPM) led by Michel Aoun shunned the meeting in protest at what the party's website described as Salam's usurping of powers reserved for the president. A Hezbollah minister said the group had boycotted in solidarity with its allies.
The presidency, reserved for a Christian in Lebanon's sectarian power-sharing system, has been vacant since last year when Michel Suleiman's term expired. Aoun is a frontrunner for the post but it cannot be filled without cross-party consensus, which he does not enjoy, and there is no sign of compromise.
Friction within Salam's government, formed last year, has escalated in recent weeks over issues including a decision to extend the term of army commander General Jean Kahwaji.
Aoun has sought the appointment of Brigadier-General Shamel Roukoz, his son-in-law, as the next army chief.
The cabinet has spared Lebanon a complete vacuum in government with the presidency vacant, and political sources say foreign governments with influence in Lebanon are determined to prevent it collapsing.
Grouping parties at opposite ends of the political spectrum, Salam's government has been largely crippled since it took office with the blessing of regional rivals Iran and Saudi Arabia, which back rival Lebanese factions.
Discontent with the paralysis has come to a head in recent weeks with a crisis over waste disposal that has triggered anti-government protests. Dozens of people were injured at the weekend when protests turned violent.
Protesters are calling another demonstration for Saturday. The government has so far failed to find a solution to the problem of where to dispose of garbage from Beirut and surrounding areas, leaving piles of rubbish to fester in the summer heat.
Ministers from Hezbollah and Aoun's FPM walked out of a another cabinet session on Tuesday, citing decrees signed without their approval as the reason for the protest.
The Salam government groups widely disparate parties including the Future Movement led by Sunni politician Saad al-Hariri, as well as Christian rivals to Aoun. (Writing by Tom Perry; Editing by Mark Heinrich)
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