(RTTNews) - A senior official at the International Committee of the Red Cross (ICRC) said Friday that relief workers are being kept out of South Waziristan region, where the civilian casualties are mounting amidst an ongoing military offensive against Taliban militants in the region.

"With regard to Waziristan in particular, lack of access prevents us from obtaining an exact picture of the humanitarian needs," Jacques de Maio, ICRC head of operations for South Asia, said Friday. "What we see now is a sharp and extremely worrying increase in the number of civilian casualties."

Maio said that aid must not be denied to those who need it. He added that humanitarian access must expand and reach a meaningful level for providing effective and unobstructed medical services for the sick and wounded in the war zones, as well as humanitarian assistance to IDPs (internally displaced people) and the families that host them.

"The humanitarian concerns must extend imperatively to all the civilians who are still in the areas, which are in the theater of military operations and armed clashes," he said. "Those are civilians trapped in the actual combat zones and we are particularly concerned about the fate of the sick and the wounded in those areas," he said.

Maio acknowledged that his organization does not have a clear picture of people who have fled the fighting until now, but added that reports suggested some 50,000 people have fled the conflict zone recently. He warned that a further 150,000 people would be displaced from the region if the conflict continues.

"It is an absolute imperative and priority that all those involved in this armed violence observe the principles of discrimination, distinction between civilians and non-combatants and actual combatants," he said, adding that the ICRC has offered its services to the Pakistani government and had requested "full access to all people deprived of freedom in relation to the situation, be they held under civilian or military authority."

Pakistani military had launched an anti-militant offensive in South Waziristan on 17th October, after final clearance from the country's government. The much-awaited offensive began after months of air raids and shelling on militant targets in the region to weaken Taliban resistance ahead of the planned ground offensive.

South Waziristan was the stronghold of former Taliban leader Baitullah Mehsud who was killed in a U.S. drone strike in August. Some 30,000 troops are involved in the offense, which pits them against an estimated 10,000 to 15,000 hard-core Taliban militants, including about 1,000 Uzbek fighters and some Arab al Qaeda members.

Though the troops are believed to have made significant gains against militants in the offensive, the Taliban fighters were reportedly offering stiff resistance to the advancing forces using rocket-propelled grenades, machine guns and anti-aircraft guns.

According to Pakistani army, at least 137 militants and 18 soldiers have been killed in South Waziristan since the offensive began Saturday. Local media reports indicate that more than 120,000 civilians have fled the war zone.

The South Waziristan offensive follows a similar offensive that was launched in the northwestern regions of Swat Valley and the districts of Dir and Buner in May. The military claims to have killed more than 1,700 Taliban militants in the five-month-long offensive, and is currently in the process of wrapping up that operation.

Despite Pakistani government's claims that the anti-Taliban operations in the Swat Valley and the neighboring Dir and Buner districts are almost over, frequent clashes between security forces and Taliban insurgents still breakout in the region.

The Pakistani army's offensive in the northwestern region was initiated after the Obama administration urged Islamabad to take on the Taliban militants it considers responsible for the escalating violence in Pakistan and neighboring Afghanistan.