BEIRUT- Lebanon's top Christian cleric took a swipe at leaders of the Shi'ite Muslim community on Sunday for making demands he said were blocking the formation of a new government and causing political paralysis in a nation in deep crisis.

Patriarch Bechara Boutros Al-Rai, leader of the Maronite church, did not mention Shi'ites directly but asked how one sect can demand "a certain ministry". Shi'ite politicians have said they must name the finance minister.

Sunday's sermon adds to tensions in a nation facing its worst crisis since a civil war ended in 1990 and where power is traditionally shared out between Muslims and Christians.

France has been pushing Lebanon to form a new cabinet fast. But a deadline of Sept. 15 that politicians told Paris they would meet has been missed amid a row over appointments, notably the finance minister, a post Shi'ites controlled for years.

Shi'ite politicians say they must choose some posts because rivals are trying to use "foreign leverage" to push them aside.

"In what capacity does a sect demand a certain ministry as if it is its own, and obstruct the formation of the government, until it achieves its goals, and so causes political paralysis" the patriarch of Lebanon's biggest Christian community said.

He said the Taif agreement, a pact that ended the 1975-1990 civil war, did not hand specific ministries to specific sects.

Prime Minister-designate Mustapha Adib, a Sunni Muslim, wants to appoint specialists and shake up the leadership of ministries.

The main Shi'ite groups - the Amal Movement and the heavily armed, Iranian-backed Hezbollah - want to select the figures to fill several posts, including the finance minister, a vital position as Lebanon navigates through its economic crisis.

A French roadmap for Lebanon includes the swift resumption of talks with the International Monetary Fund, a first step to helping deal with a mountain of debt and fix Lebanon's broken banking sector. But it first needs a government. (Writing by Edmund Blair; Editing by Alex Richardson) ((edmund.blair@thomsonreuters.com; Reuters Messaging: edmund.blair.thomsonreuters.com@thomsonreuters.net))