The prisoners were shown on al-Jazeera TV

Robert Hutchinson, spokesman for Jane's Defence Weekly, told BBC News Online the use of untrained personnel was likely to be examined and improvements made to the way convoys were guarded.

He said Iraqi "guerrilla warfare" tactics had "wrong-footed" coalition troops and may have contributed to the capture of the two civilian lorry drivers.

They had been employed to deliver food aid to Iraqi prisoners of war by the Ministry of Defence, which criticised Arab TV station al-Jazeera for showing footage of them.

An MoD spokeswoman said the drivers - thought to be Kenyans - had been separated from a guarded convoy after it was halted by a "civil disturbance".

Guerrilla tactics

Although the MoD would not say how many civilians were working for it in Iraq, Mr Hutchinson said: "The British Army has always used local labour and these are probably individuals who were in the Gulf."

Local drivers are being used to deliver aid

He said the length of many of the convoys - which carry vital supplies to troops, prisoners and Iraqi people - had made them more difficult to defend, and Iraqi forces still posed a threat.

"It may be they thought a particular area was clear of Iraqi military," Mr Hutchinson said.

"But, of course, the Iraqi military have been operating guerrilla tactics and this may not have come into their plans quite so much as it should have done."

'Long lines'

Mr Hutchinson said the situation in Iraq remained "fluid" and that the type of Iraqi resistance troops are facing may not have featured prominently when the plans were drawn up.

"It has probably caught them wrong-footed practically," he said. "They are re-assessing their tactics as a result of the type of tactics they are encountering."

On Wednesday the US announced that a further 30,000 troops were being sent to the Gulf, many of which would likely be deployed to defend convoys, Mr Hutchinson said.

Military commanders would want to "protect those long lines of communication", he explained.

'Concerted force'

The problems of defending supply routes was further highlighted by the plight of the first US troops to be captured.

They had been setting up a supply base and "were not armed to fight a concerted force".

The treatment of any captured personnel would depend very much on exactly which regiment was holding them, Mr Hutchinson said.

In the first Gulf War some pilots shot down were treated badly while others had fared relatively well, he said.

The MoD has not yet confirmed the nationality of the captured civilian workers, although it has informed their Saudi Arabian employers of their capture.

The Kenyan High Commission is investigating claims they are Kenyan citizens.

The MoD told BBC News Online it appeared the two drivers had been captured after they failed to make a turning and became separated from the rest of the aid convoy.