"The different opinions that tore us apart in February should be a cautionary warning to us all," Robertson told delegates as the spring session of NATO's parliamentary assembly opened in the Czech capital.

"If the free world is going to indulge itself in open disagreements and verbal conflicts, you'd better remember that the terrorist community is not divided they are single minded," he continued.

Robertson warned that terrorist groups would "be inspired and not deterred by the fact that the great nations of the free world have such public arguments as well."

"You can occasionally afford to have divisions in an Alliance especially in an alliance made of democracies. But you can't (do so) much more than once in ten years."

"To face the challenges of the future we have to become more united and less self indulgent than we have allowed ourselves to be, it is the only way that will guarantee our freedom."

"Would we be talking here in a free Prague if NATO had not remained united in the 40 years of the Cold war?" Robertson asked the assembly.

"But I am not pessimistic. They are not wounds that are fatal," he added.

The North Atlantic Alliance was seriously split by a crisis over Iraq sparked by three anti-war member states -- France, Germany and Belgium -- over whether it should boost NATO member Turkey's defences in preparation for the war.

The NATO parliamentary assembly links more than 200 lawmakers from the alliance's 19 members together with associated states including Russia, meeting in full session twice yearly.

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