Officials have said that NATO apologized on Wednesday for the shooting deaths of four unarmed Afghan civilians and for wrongly labeling two of them "known insurgents."

The New York Times has reported that the shootings on Monday were the latest in a succession of events where civilians have been killed by military convoys at NATO or U. S. checkpoints.

The newspaper also said that Afghan leaders have been angered by the killings, which have undermined NATO and U. S. plans as they enter a crucial phase centered on a summer offensive in Kandahar.

It will send training teams into Afghanistan so troops can "implement critical lessons learned from previous incidents," NATO has said.

However, according to observers the damage may already be done.

One tribal elder in Kandahar, said, "People hate the international forces. Their presence at the moment is too risky for ordinary people. They are killing people, and they don't let people travel on the road."

The Times further reported that Maj. Gen. Mike Regner, a NATO official, said commanders "at all levels are increasing efforts to protect the Afghan people affected by our operations."

It was also noted by the Times that Afghan and NATO investigators are reviewing the shooting but say a "formal, more thorough joint investigation may also be conducted." (With Inputs from Agencies)