WARSAW, June 7: Nato boosted ties with Ukraine on Monday by signing an agreement to use its eastern neighbour's transport planes but said the country must build a functioning democracy before it is ready for membership.

Nato and Ukraine signed a "memorandum of understanding on strategic airlift", which one NATO official described as setting out a framework for future cooperation.

"It gives Ukraine an idea of how much NATO could request and gives NATO an idea of what Ukraine has to offer, though nothing's set in stone and no money's changing hands," the official said.

NATO Secretary-General Jaap de Hoop Scheffer said the alliance valued its relationship with Ukraine, but repeated calls for reform. "Strengthening of democratic institutions, development of civil society and guarantee of rule of law are all crucial preconditions for bringing Ukraine closer to the fulfilment of its legitimate Euro-Atlantic integration inspiration," Scheffer told delegates at a NATO-Ukraine meeting in Warsaw.

He later told a news conference the alliance was grateful for Ukraine's participation in peacekeeping operations. "We could not do without Ukraine," he said. Ukraine has often indicated its desire to join NATO and has been praised for sending troops to Iraq and Kosovo.

But Western allies have criticized Ukraine's lack of media freedom and its failure to implement market reforms and stamp out corruption. The new agreement is meant to give NATO better access to Ukraine's giant Antonov Ruslan aircraft to get troops, kit and supplies to distant war zones.

The aircraft are also in great demand for delivering heavy equipment around the world. The United States has more than 200 strategic lift planes but among its European allies only Britain, with four leased C-17s, has a similar capability.

Ukraine, a country of 48 million people, is sandwiched between the expanded European Union and Russia, which has retained its strong influence in the years following the break up of the Soviet Union and Ukraine's independence. -Reuters