By Steven Scheer
JERUSALEM, Nov 14 (Reuters) - Israeli energy company shares slid for a second straight session on Sunday, extending Thursday's losses on news a finance ministry panel said the government should sharply raise its take on oil and gas revenue.
An advisory committee's interim report recommended keeping the royalty rate at 12.5 percent while adding a "progressive tax" in a 20-60 percent range, depending on production yields. A final report was expected soon.
"The interim recommendations will essentially change the valuation picture of energy partnerships," said IBI Investment House analyst Guil Bashan.
Bashan lowered his rating for Isramco, one of the partners in a group exploring for natural gas, to "reduce" from "buy" and his price target to 0.33-0.47 shekel from 0.64 shekel.
U.S.-based Noble Energy leads a group with two units of conglomerate Delek Group drilling for natural gas and oil off Israel's Mediterranean coast.
The group, which includes Avner Oil Exploration, Delek Drilling and Isramco, has discovered reserves of 8.4 trillion cubic feet at the Tamar drilling site, 90 kilometres offshore.
Officials have projected a gross of $4 billion from Tamar and a second site nearby named Leviathan.
Delek Drilling shares sank 9.1 percent, while Avner -- also a Delek unit -- fell 6.8 percent after falling 6.2 percent and 4.9 percent, respectively, on Thursday. Isramco shares slid 8.2 percent.
Overall, the blue-chip Tel Aviv 25 index fell 0.9 percent while the broader TA-100 closed 1.1 percent lower.
The companies have vowed to fight the recommendations, saying higher taxes should be for future exploration since the consortium had invested millions of dollars into the projects based on the current tax rates.
The advisory committee's chairman, Hebrew University economist Eytan Sheshinski, said much of the world had raised its share of revenues from natural resources, while Israel has maintained the same level since 1952.
"Without a doubt, the public does not receive its proper part of the revenues from natural resources," Sheshinski said on Wednesday.
($1 = 3.68 shekels)