Voices expressing concern over the armed forces' failures are getting louder. One Israeli cabinet minister said last week: 'We gave the army so much money. Why are we getting these results?' Last week saw Hizbollah's guerrilla force, dismissed by senior Israeli military officials as 'ragtag', inflict further casualties on one of the world's most powerful armies in southern Lebanon. At least 12 elite troops, the equivalent of Britain's SAS, have already been killed, and by yesterday afternoon Israel's military death toll had climbed to 45.

As the bodies pile up, so the Israeli media has begun to turn, accusing the military of lacking the proper equipment, training and intelligence to fight a guerrilla war in Lebanon. Israel's Defence Minister, Amir Peretz, on a tour of the front lines, was confronted by troubled reserve soldiers who told him they lacked proper equipment and training.

Israel's chief of staff, Major-General Dan Halutz, had vowed to wipe out Hizbollah's missile threat within 10 days. These claims are now being mocked as rockets rain down on Israel's north with ever greater intensity, despite an intense and highly destructive air bombardment.

As one well-connected Israeli expert put it: 'If we have such good information in Lebanon, how come we still don't know the hideout of missiles and launchers?... If we don't know the location of their weapons, why should we know which house is a Hizbollah house?'

As international outrage over civilian deaths grows, the spotlight is increasingly turning on Israeli air operations. The Observer has learnt that one senior commander who has been involved in the air attacks in Lebanon has already raised concerns that some of the air force's actions might be considered 'war crimes'.

Yonatan Shapiro, a former Blackhawk helicopter pilot dismissed from reserve duty after signing a 'refusenik' letter in 2004, said he had spoken with Israeli F-16 pilots in recent days and learnt that some had aborted missions because of concerns about the reliability of intelligence information. According to Shapiro, some pilots justified aborting missions out of 'common sense' and in the context of the Israeli Defence Force's moral code of conduct, which says every effort should be made to avoiding harming civilians.

Shapiro said: 'Some pilots told me they have shot at the side of targets because they're afraid people will be there, and they don't trust any more those who give them the coordinates and targets.'

He added: 'One pilot told me he was asked to hit a house on a hill, which was supposed to be a place from where Hizbollah was launching Katyusha missiles. But he was afraid civilians were in the house, so he shot next to the house ...

'Pilots are always being told they will be judged on results, but if the results are hundreds of dead civilians while Hizbollah is still able to fire all these rockets, then something is very wrong.'

So far none of the pilots has publicly refused to fly missions but some are wobbling, according to Shapiro. He said: 'Their target could be a house firing a cannon at Israel and it could be a house full of children, so it's a real dilemma; it's not black and white. But ... I'm calling on them to refuse, in order save our country from self-destruction.'

Meron Rappoport, a former editor at the Israeli daily Haaretz and military analyst, criticised the air force's methods for selecting targets: 'The impression is that information is sometimes lacking. One squadron leader admitted the evidence used to determine attacks on cars is sometimes circumstantial - meaning that if people are in an area after Israeli forces warned them to leave, the assumption is that those left behind must be linked to Hizbollah ... This is problematic, as aid agencies have said many people did not leave ... because they could not, or it was unsafe to travel on the roads thanks to Israel's aerial bombardment.'

These revelations raise further serious questions about the airstrike in Qana last Sunday that left dozens dead, which continues to arouse international outrage. From the outset, the Israeli military's version of events has been shrouded in ambiguity, with the army releasing a video it claims shows Katyusha rockets being fired from Qana, even though the video was dated two days earlier, and claiming that more than 150 rockets had been fired from the location.

Some IDF officials have continued to refer vaguely to Katyushas being launched 'near houses' in the village and to non-specific 'terrorist activity' inside the targeted building. In a statement on Thursday, the IDF said it the air force did not know there were civilians in what they believed was an empty building, yet paradoxically blamed Hizbollah for using those killed as 'human shields'.

Human rights groups have attacked the findings as illogical. Amnesty International described the investigation as a 'whitewash', saying Israeli intelligence must have been aware of the civilians'.

One Israeli commander from a different squadron called the Qana bombing a 'mistake' and was unable to explain the apparent contradiction in the IDF's position, although he insisted there would have been no deliberate targeting of civilians. He said he had seen the video of the attack, and admitted: 'Generally they [Hizbollah] are using human shields ... That specific building - I don't know the reason it was chosen as a target.'