Almost 150 NATO oil tankers and supply trucks turned to ashes and at least 20 people were killed in Pakistan with 29 more containers burnt in a sixth terrorist attack on Saturday morning since the beginning of October.

Pakistan imposed a blockade on supply to the NATO trucks on Oct. 1, following an incursion by U.S.-led NATO gunship helicopters on May 30 that killed three paramilitary troops at a checkpoint on Pakistan-Afghanistan border in the troubled North Waziristan tribal area in northwest Pakistan.

The Pentagon, NATO and the U.S. envoy in Islamabad have apologized on the incursion after an investigation this week that found NATO forces guilty. However, Pakistani foreign office stated that no decision on reopening the Torkham border in the northwest has yet been taken.

Earlier this week, Pakistani foreign office spokesman Abdul Basit told Xinhua in an interview that NATO supply blockade is put due to security concern and the borders will be reopened as soon as the situation is improved.

The fire that destroyed 29 NATO supply oil tankers at 1:30 a.m. local time Saturday morning at Mithri, in district Bolan of southwest Balochistan province of Pakistan, was still burning after nine hours, as only one fire tender was available in the remote area to fight the blaze, local sources told Xinhua.

A dozen of unidentified armed men riding four motorcycles fired a rocket and shot volley of fires at the NATO tankers, eyewitnesses and police said. No group has so far accepted the responsibility for the inferno, which also gutted four nearby shops as well, eyewitnesses said.

The convoy was on way to Afghanistan through Chaman at the Pakistan-Afghanistan border, which is now partially open to NATO supply. The gates of the other entry point into Afghanistan, Torkham in the northwest Khyber Pakhtunkhwa province, remained shut on the tenth day.

In the first incident in October over 35 NATO tankers were burnt in Shikarpur in the southern Sindh province while two more were destroyed in southwest Balochistan province the same day. Two days later, 20 tankers were set ablaze in the garrison city of Rawalpindi near capital Islamabad.

In the third incident some two dozens were destroyed near Quetta, Balochistan shortly before over 50 tankers were torched to ashes in Nowshehra in the northwest on Wednesday. In June, one major attack on NATO supplies set fire on 60 trucks near Islamabad.

Disbanded Tehrik-e-Taliban Pakistan (TTP) had accepted the responsibility of all the incidents as Taliban spokesman Azam Tariq vowed to continue attacks on NATO supplies.

However, some local analysts rule out Taliban's involvement in attacks on NATO convoys in Balochistan, as they believe TTP is not that influential in Balochistan as in Khyber Pakhtunkhwa province. However, analysts believe that different criminal groups including some Baloch insurgents might be involved in these attacks.

Although NATO claims that current block to its supply in Pakistan has not affected its over 140,000 troops stationed in Afghanistan fighting insurgency since ouster of Taliban government in 2001, its desperation exhibits that NATO has started feeling the heat of the blockade, local watchers believe.

Both NATO and Pakistan inked a controversial transit agreement in 2001 that allows "all kinds" of "customs inspection and tax free" supplies into Afghanistan. Local media reports suggest that the compromised agreement earns Islamabad some 1.5 billion dollars annually.

Over 70 percent of supplies and 40 percent of NATO's oil needs in Afghanistan are being supplied through Pakistan. Some 7,000 contracted truckers with NATO-paid private security responsible for convoys safety are involved in the project.

Taliban started attacking NATO supply convoys in 2008. They turned the heat on the next year with the intensified operation by Pakistani troops to wipe out a seven-year-old insurgency in the rugged northwest tribal areas. However, with recent violation of Pakistani airspace, Taliban have unleashed a fury on NATO interests which still seems to be galloping unbridled, as local analysts speculate more fireworks in the coming days.