By Patrick Markey and Aseel Kami
BAGHDAD (Reuters) - Iraqi Sunni Muslim and Kurdish ministers boycotted a cabinet session on Tuesday to show support for protests that are threatening Shi'ite Prime Minister Nuri al-Maliki's fragile cross-sectarian government.
Thousands of protesters have demonstrated and blocked a key highway in Iraq's Sunni provinces for more than two weeks to challenge Maliki, a leader many Sunnis feel has marginalized their community a year after the last U.S. troops pulled out.
In a rival show of backing for the Shi'ite premier, around 7,000 protesters marched on Tuesday in the southern cities of Basra and Kerbala, waving Maliki portraits and banners supporting the Shi'ite parties in his coalition.
Protests and the conflict in nearby Syria, where mainly Sunni insurgents are fighting President Bashar al-Assad, an ally of Shi'ite Iran, are fuelling worries that Iraq risks sliding back into the sectarian slaughter that peaked in 2006 and 2007.
Sunni-backed Iraqiya party lawmakers said their ministers stayed away from the cabinet meeting in support of the protests sparked in late December when security forces arrested bodyguards of Sunni Finance Minister Rafaie al-Esawi.
"They made a decision to boycott the session today," Iraqiya lawmaker Jaber al-Jaberi said. "They don't see a response from the government to the demands of the protesters... or to accepting power-sharing."
Alaa Talabani, a Kurdish lawmaker, said party leaders had also asked Kurdish ministers to stay away. A senior government source at the meeting confirmed Sunni and Kurdish ministers had missed the Council of Ministers session.
Violence and bombings are down sharply since the height of the OPEC country's conflict, but the government, split among Shi'ites, minority Sunnis and ethnic Kurds, has been deadlocked over power-sharing since it was formed in December 2010.
Complicating the crisis is a growing dispute between the Arab-led government in Baghdad and autonomous Kurdistan in the north, where ethnic Kurds run their own regional authority.
Tensions have worsened since Kurdistan signed oil deals with majors such as Exxon Mobil and Chevron, a move seen by Baghdad as an unconstitutional challenge for control of Iraq's crude.
In the Sunni heartland of Anbar province, once a base for Sunni Islamist fighters and al-Qaeda insurgents battling U.S. troops, at least 5,000 protesters have taken daily to the streets and blocked a highway leading to the Syrian border.
Sunni leaders and tribal sheikhs' demands range from Maliki's removal to release of detainees and the suspension of an anti-terrorism law that Sunnis believe has been abused by authorities to target their sect unfairly.
Some Sunni politicians now sense a chance in the conflict across the border in neighboring Syria against Assad, an Iran ally whose minority Alawite sect has roots in Shi'ite Islam.
Should Assad fall, a Sunni regime may rise to power in Syria, weakening the influence of Iran in the region's Shi'ite-Sunni power balance and embolden Iraq's own Sunni minority.
Lawmakers from the Sunni-backed Iraqiya block, Maliki's State of Law Shi'ite alliance, Kurdish parties and other Shi'ite parties failed to agree over the weekend on talks in parliament to discuss the demands of protesters.
Demonstrations erupted a day after President Jalal Talabani flew out of Iraq for treatment following a stroke. A respected Kurdish statesman, Talabani has long been a moderating influence among Shi'ite, Sunni and Kurdish factions.
(Reporting by Raheem Salman and Aref Mohammed in Basra; Editing by Alistair Lyon)