UPDATE 1-NATO has plans to defend Turkey if need be -Rasmussen

(Updates, recasts)

BRUSSELS, Oct 9 (Reuters) - The head of NATO said on Tuesdaythat the 28-member military alliance had plans in place todefend Turkey against attack from Syria if necessary, but thathe hoped the two countries would find a way to stop tensionsescalating.

NATO ambassadors threw their support behind Turkey in anemergency meeting last week after Syrian shells struck a bordertown in Turkey killing five civilians.

The two neighbours have repeatedly exchanged fire sincethen, the most serious outbreak of cross-border violence sinceSyria's revolt against President Bashar al-Assad erupted 18months ago.

"We have all necessary plans in place to protect and defendTurkey if necessary," Secretary-General Anders Fogh Rasmussentold reporters before a meeting of the alliance's defenceministers in Brussels.

On Monday, Turkish President Abdullah Gul said the"worst-case scenarios" were now playing out in Syria and thatTurkey would do everything necessary to protect itself.

Gul said that the violence in Turkey's southern neighbour,where a revolt against Assad has evolved into a civil war thatthreatens to draw in regional powers, could not go onindefinitely.

U.N. Secretary-General Ban Ki-moon said on Monday theescalation of the conflict along the Turkey-Syria border and theimpact of the crisis on Lebanon were "extremely dangerous".

The Turkish army fired back on Monday for a sixth day aftera shell from Syria flew over the border and has bolstered itspresence along the 900-km (560-mile) frontier in recent days.

Rasmussen commended the Turkish government for itsrestraint, saying he hoped the parties would avoid an escalationof the crisis.

"Obviously Turkey has a right to defend herself withininternational law," he said. "I would add to that that obviouslyTurkey can rely on NATO solidarity."

Turkey joined NATO in 1952.

(Reporting by Adrian Croft; Writing by Sebastian Moffett;Editing by Andrew Osborn)