Baku, July 20 (AZERTAC). Some of China`s biggest companies, from tech giants to airlines and retailers, are warning of unexpectedly sharp drops in profit of up to 80 percent, adding to pressure on Beijing to reverse a painful economic slump.

On Wednesday, Air China Ltd., one of three main government-owned airlines, warned first-half profit will fall by at least half from a year earlier. State-owned ZTE Corp., one of the world`s biggest producers of telecommunications equipment, is projecting a decline of up to 80 percent.

The woes facing even politically favored companies that benefit from monopolies, low-cost bank loans and other government aid highlight the challenges for the authoritarian country`s leaders who are trying to pull China out of its deepest slowdown since the 2008 crisis.

Forecasters say the slowdown might have bottomed out after growth fell to a three-year low of 7.6 percent in the second quarter but the timing and strength of a rebound are uncertain. Premier Wen Jiabao warned last weekend a recovery was not yet stable. On Tuesday, he said the employment outlook "will become more complex and severe."

Industries that rely on demand for new factories and equipment have been hurt as struggling manufacturers put off spending and Beijing enforces curbs imposed on home purchases to cool surging prices. The country`s shipbuilding industry association, slammed by weak trade, says May orders for new vessels were half the level of a year earlier.

Da Ming International Holdings Ltd., which says it is China`s biggest processor of stainless steel used in manufacturing automobiles, appliances and other products, warned Wednesday it expects to suffer a first-half loss due to falling prices for its products.

AP researchers Yu Bing in Beijing and Fu Ting in Shanghai contributed.