"The Taliban and Al-Qaeda are no longer capable of acting in a military sense of the word... but Hekmatyar obviously has the money, the influence, the political will and power to reorganise these remnants of Al-Qaeda and Talibs on one side and regroup them into new groups under his political leadership and then let them conduct terrorist attacks like the one we saw last night," German Lieutenant Colonel Thomas Loebbering told reporters.

"For us this is an option, it is not for sure, but it is an option of what we think is the most realistic one."

Extremists linked to hard-line Islamist warlord Hekmatyar, who the U. S. A. has declared a terrorist, have been blamed for a number of attacks on government and foreign targets aimed at destabilising President Hamid Karzai’s administration.

The two 122 mm rockets were launched at around 10:45 pm (0615 GMT) one of them exploding inside the ISAF headquarters compound and the second impacting northeast of Camp Warehouse, the headquarters of the Kabul Multinational Brigade.

The first rocket caused minor damage to one building and two ISAF vehicles in the ISAF headquarters, Loebbering said, adding there were no casualties.

Although ISAF has come under around a dozen rocket attacks since its inception in December 2001, Loebbering said Sunday’s attack was the first direct hit on any ISAF facility and indicated an increasing sophistication on the part of the attackers.

"As we now know that this was a 122 mm rocket which can be launched exactly we do believe this was targeted at ISAF directly," he said.

"This is a significant difference from the type of attacks we have experienced so far; it is far more sophisticated."

The latest rocket attack followed a deadly ambush on a U. S. patrol in southwest Helmand province a day earlier in which two Special Forces Operations members were killed, and an incident in which U. S. Special Forces observing Afghan militia operations came under attack in neighbouring Kandahar province.

"We are considering whether there might be any connection or countrywide coordination in these attacks," Loebbering said. Hekmatyar has been collecting, reorganising and training Taliban and Al-Qaeda remnants since last year, he said. "There has been a remarkable political change in the activities of Hekmatyar," he added.

Loebbering said over the past several weeks there had been reorganisation and regrouping taking place in southeast Afghanistan involving Taliban and Al-Qaeda remnants and Hekmatyar. "There are more and more closer connections between these two groups," he said.

Hekmatyar is believed to have between 15-35 mobile training camps concentrated in southern and eastern Afghanistan which are constantly on the move. From last year’s experience, Loebbering said the number of camps was expected to increase as spring progressed, even as coalition forces were tracking them down. The 4,700-strong ISAF force comprises troops from 28 nations and is currently led by Germany. Loebbering said a decision was expected in April on which nation would lead the next ISAF contingent from August 10, when the current German-Dutch term expires. ISAF is responsible for security in Kabul, while a 11,500-strong U. S.-led coalition force is hunting down Taliban and Al-Qaeda remnants across the central Asian nation.