Cairo/Washington: Even as the US on Thursday mulled the possibility of air strikes and other options to stop Libyan Army, forces loyal to Muammar Gaddafi inched closer to the rebel-stronghold of Benghazi amid fierce battle in the last major town of Ajdabiya.

Heavy fighting raged around the key town of Misurata and Ajdabiya, as rebel forces made last ditch efforts to stop two tanks-led columns closing on the two port cities of Benghazi and Tobruk, which would give the Libyan leader total sway over his country.

The rebels claimed to have shot down two fighter aircraft bombarding Benghazi amid reports that at least 30 people were killed and several wounded in the fighting.

Al Jazeera quoted state-run Libyan television as saying that Gaddafi's forces were on the outskirts of Benghazi.

"The town of Zuwaytinah is under control (of loyalists) and armed forces are on the outskirts of Benghazi," the Arab channel said.

US for steps beyond 'no fly' zone

Wary of the speed at which Gaddafi's forces were moving, the White House pushed for an international response in Libya as a top US official said Washington was contemplating steps that could go beyond a 'no fly' zone.

As intense battles raged, the UN Security Council was all set to meet to vote on a draft resolution that would not only introduce a 'no fly' zone over Libya, but may also authorise the use of air strikes to stop the advance of Gaddafi's forces.

Susan Rice, US Ambassador to the UN, said, "We are discussing very seriously and leading efforts in the Council around a range of actions that we believe could be effective in protecting civilians".

Top US officials said military action could be directed not only at Gaddafi's Air Force, but at artillery and communications systems too.

Deadline to capture twin cities

Apprehending a combined western move against him under the aegis of the UN Security Council, Gaddafi's son Saif al-Islam has set a "48 hours" deadline for his forces to capture the twin cities of Benghazi and Tobruk, a report said.

Facing an unprecedented month-long uprising against his 41-year-old rule, Gaddafi unleashed his forces to wrest back territories seized by the rebels, Al Jazeera channel said.

The battle appeared to be uneven as TV images showed burnt out vehicles of the rebel forces in a roadside just outside Ajdabiya, while Libyan government forces displayed tanks, artillery guns, mortars and mobile rocket launchers, much heavier weapons than used by the opposition forces.

The western powers apprehend that Gaddafi's forces would use fighter jets to bombard urban areas of Benghazi.

Martin Nesirky, a spokesman of Ban Ki-moon, said the Secretary-General was ‘gravely concerned’ about signs that Gaddafi was preparing to attack Benghazi.

Al Jazeera quoting residents in Misurata and Ajdabiyah said pitched battles were going on in and around the two key towns. Misurata is 150 km from the capital Tripoli while Ajdabiyah guards the road to Tobruk and the Egyptian border in the rebel-held east.

Gaddafi told a group of young people from Misurata that "battle continues at Misurata that will be the decisive battle".

"You are going to be called to take up arms and will take part in the battle," he was quoted as saying.

Gaddafi urged the gathering "not to leave Misurata hostage in the hands of a handful of madmen".

Linking the rebels with al-Qaeda, Gaddafi said he would not hold dialogue with them.

As the defiant leader's well-trained and heavily-armed forces registered major successes in recent days, a rebel spokesman in Misurata claimed on Wednesday that they had beaten back an attack by Libyan forces on the city, killing 80 of Gaddafi's men.

Lobbying against Gaddafi at UN

At the UN headquarters in New York, Ibrahim Dabbashi, Libya's deputy envoy to the UN who had turned against Gaddafi, called on the Security Council to pass fast a resolution imposing a no-fly zone over the North African country.

As the 15-member body debated the draft resolution to impose a no-fly zone over Libya, Dabbashi asked the world community to act quickly and warned of "genocide" Ajdaibya and "ethnic cleaning" in villages in the western part of the country.

"We think that in the coming hours we will see real genocide in Ajdabiya," he said. "The international community has to act within the next ten hours."

Dabbashi also expressed confidence that the present draft resolution would be modified to include "air strikes."

The text of the draft resolution, co-authored by Britain and France, was circulated by Lebanon, a non-permanent member of the Council, on Tuesday.

Separately, the UN Security Council rejected a Russian proposal to pass a smaller resolution calling for a ceasefire in Libya. "We did come up with the idea of doing a brief but punchy ceasefire resolution," Russian envoy to the UN Vitaly Churkin said.

In Washington, White House Press Secretary Jay Carney expressed hope that the US-led international community would move quickly on Libya.