NATO agreed Friday to buy five reconnaissance drones to boost the alliance's surveillance capabilities after the Libyan air war exposed shortcomings among European forces in that field.

The Global Hawk, a long-range, high-altitude aircraft made by US defence industry giant Northrop Grumman, will be the key component in NATO's long-delayed Alliance Ground Surveillance (AGS) system.

"This will give our commanders the ability to see what is happening on the ground at long range and over periods of time, around the clock, and in any weather," said NATO Secretary General Anders Fogh Rasmussen.

"Our recent operation to protect civilians in Libya showed how important such a capability is," Rasmussen told a news conference after a two-day meeting of NATO defence ministers.

The United States provided the vast majority of drones and surveillance aircraft during the Libyan air war, and NATO has since then made purchasing such technology a priority.

The Global Hawk can stay aloft for 24 hours at an altitude of 18,300 metres (60,000 feet).

A group of 13 countries will acquire the AGS system: Bulgaria, Czech Republic, Estonia, Germany, Italy, Latvia, Lithuania, Luxembourg, Norway, Romania, Slovakia, Slovenia and the United States.

The main operating base will be at NATO's Sigonella air base in Sicily.

The programme, two decades in the making, was finally agreed after a deal was found on how to pay for it.

Britain and France will not participate in the financing but will instead allow the 28-nation alliance to use their own surveillance aircraft.

London is offering the use of its Sentinel surveillance plane while Paris will contribute with its future Heron TP drone, based on Israeli technology.