CAIRO (Reuters) - Egypt's Case 30 index posted its sharpest single-day drop in almost four months on Sunday after the central bank raised interest rates and Egypt's government boosted some taxes and energy prices.

The index, up 9 percent this year to last week's close, dropped 2.6 percent to 11,246.29 points as shares of market heavyweight Orascom Construction Industries (OCI) tumbled.

The Egyptian government said last week it would raise gas prices for energy-intensive companies and tax companies in some free-zones. The country's central bank raised interest rates last week by 50 basis points to contain inflation.

"There are a lot of decisions investors are unhappy with," said Hashem Ghoneim, chief executive of El Nour Securities in Cairo.

OCI extended declines to a fifth consecutive session, dropping 4.38 percent to 396 Egyptian pounds.

Shares is the company have dropped about 14 percent since the government said it would tax income in some free zones, where the company has fertiliser operations.

"The initial drop in the stock price last week was understandable...but the drop in OCI's stock price today has gone beyond that which is fundamentally warranted and is part of perhaps a general decline in the market," said Tarek Shahin, construction analyst at Beltone Financial in Cairo.

Banking shares also fell as investors feared the interest rate rise and a government decision last week to tax treasury bill interest could hurt profits, Ghoneim said.

Commercial International Bank, the country's largest listed lender, tumbled 4.6 percent to 84 pounds. Credit Agricole Egypt

shed 3 percent to 21.85 pounds.

The Hermes index retreated 2.44 percent to 97,683.32 points and the broader CIBC index shed 0.7 percent to 581.16 points.

"Our market was expensive and it took a nice correction," Ghoneim said. "Hopefully it will hit a bottom soon."