UPDATE 1-Delek revises up Israel natgas field deposits

* Says deposits to meet Israel's demands for 20 years

* Brokerage raises Tamar site market value to $4.55 billion

(Adds brokerage ups Tamar market value, paragraph 8)

JERUSALEM, Aug 11 (Reuters) - A consortium leading natural gas explorations off Israel's coast on Tuesday raised the volume of deposits it has found to 7.3 trillion cubic feet (207 billion cubic meters), up 16 percent from earlier estimates.

Delek Drilling (DEDRp.TA) said in a statement to the Tel Aviv Stock Exchange Noble Energy (NBL.N), the leader of a group drilling at the Tamar well in the Mediterranean, raised the gross mean resource estimates of the deposits.

Noble and its Israeli partners have been drilling at three sites off Israel's shore. The Tamar-1 and Tamar-2 sites are about 90 km (56 miles) off the northern port of Haifa. Dalit is off the country's southern coast.

Noble last month raised the gross mean resource estimate for Tamar to 6.3 trillion cubic feet (178 billion cubic metres), 26 percent up from initial estimates, and analysts said the total revenues from the site could top $38 billion. [ID:nWNAB5053]

Noble owns 36 percent of the Tamar sites while Isramco Negev (ISRAp.TA) owns 28.75 percent, and Delek Group DELKG.TA has a 31 percent stake through two units that have equal shares: Avner Oil Exploration (AVNRp.TA) and Delek Drilling. Dor Gas Exploration owns 4 percent.

Billionaire Yitzhak Tshuva, who has a 62 percent majority share in Delek Group, told Israel Radio on Tuesday the deposits at the three sites would meet Israel's growing natural gas demands for 20 years.

The consortium plans to bring the first phase of production to Israeli shores by 2012.

The Psagot brokerage said the new estimates brought Tamar's market value to $4.55 billion from $4.33 billion.

Shares of Delek Drilling were up 2.63 percent in the afternoon in Tel Aviv compared with a 0.87 percent drop in the general bourse. Avner Oil Exploration was up 2.66 percent and Isramco Negev was up 2.83 percent.

Israel is also receiving natural gas from Egypt under a 20-year deal signed in 2005.

($1 = 3.85 shekels) (Reporting by Joseph Nasr; editing by James Jukwey)