* Aleppo rebel council has stockpiled staple goods-president

* Syrian govt, allied forces effectively blockade Aleppo

* Opposition looking at “alternative ways” into Aleppo

BEIRUT/AMMAN, July 12 (Reuters) - Rebel areas of Aleppo have stockpiled enough basic supplies to survive months of siege by pro-Syrian government forces that cut off their half of the city last week, even though some goods are already in short supply, an opposition official said.

Syrian government forces backed by allies including Lebanon’s Hezbollah and the Russian air force last week advanced to within a few hundred metres of the only road into the rebel-held area of Aleppo, making it impassable for the several hundred thousand people living under rebel control in Aleppo.

The advance has brought Damascus closer to achieving its long-held aim of fully encircling rebel-held areas of Aleppo, a major symbol of the uprising against President Bashar al-Assad now in its sixth year.

Rebel forces are fighting back in an attempt to reopen the Castello road. The opposition does not expect the Syrian army and its allies to storm the populous, rebel-held sector of Aleppo, and is preparing for the possibility of a long siege.

As prices sky-rocket, opposition authorities are seeking to ration consumption, to prevent hoarding, and to regulate prices so traders do not overcharge, said Brita Hagi Hassan, president of the city council for opposition-held Aleppo. He said opposition authorities were also moving towards opening “alternative ways” into the rebel-held part of the city.

“We have the capability to open new ways because the situation is still under control,” Hassan told Reuters. The plans were secret, he added, speaking from rural areas west of Aleppo after twice failing to enter the city last week.

Prices of non-perishable staple foods have tripled and fresh produce has gone up by even more - if it is can be found at all. A kilo of tomatoes, which are now in season, cost at least five times more than they did before the blockade.

AIR STRIKES

The city council had stockpiled flour, wheat, fuel, sugar and rice, and residents were being urged to adapt to the new situation, Hassan said. “I reassured people on this matter ... we can remain for several months without a problem,” he said.

“There are posters, pamphlets and there will be a press conference about this matter, so that the people are aware of the new situation, because the situation is very bad.”

Operators of generators had been told to cut back their use to two hours a day, and the council had set aside fuel for essential uses such as bakeries.

As part of their counter attack, rebel groups had heavily shelled government-held areas of Aleppo, where the population is estimated at slightly over 1 million people. Air strikes have also targeted rebel-held areas of the city.

“The streets are abnormally quiet after several barrel bombs hit our neighbourhood. People are waiting,” said Malek Idrees, a father of five who lives in rebel-held Aleppo.

“I could not find fresh produce for the last two days even but there are no severe shortages with most goods still in the markets,” he told Reuters from the city. “I could not find bread yesterday,” he added.

The United Nations said it was deeply concerned about increased fighting in and around Aleppo and called for humanitarian aid access and the safe and rapid evacuation of civilians.

U.N. spokeswoman Alessandra Vellucci said that intensified hostilities between government forces and armed groups had cut off 300,000 people.

Hassan put the population in rebel-held Aleppo at 400,000.

Assad is supported by Moscow, which launched air strikes in September, as well as Iranian fighters and Lebanese Shi’ite Hezbollah fighters. Hezbollah has said it sees Aleppo as the most important battle in Syria, equating it with the defence of the capital Damascus.

Assad’s allies say they are battling the al Qaeda-linked Nusra Front in Aleppo. But Western-backed nationalist insurgents loosely grouped under the banner of the Free Syrian Army (FSA) say they control the rebel-held part of the city. (Writing by Tom Perry; Editing by Dominic Evans and Ralph Boulton)