Several Scud missiles fired at rebels by Syria have landed "fairly close" to the Turkish border, NATO's top military commander said on Friday in a blog explaining why Patriot anti-missile batteries are being deployed to Turkey.

The comments by U.S. Admiral James Stavridis, NATO's Supreme Allied Commander Europe, were the first to confirm that Scuds have come down near the border of Turkey, a NATO-member state.

Stavridis also described the situation in Syria as "chaotic and dangerous".

U.S. and NATO officials said on Wednesday that Syrian President Bashar al-Assad's forces had fired Scud-style ballistic missiles at rebels in recent days in what U.S. officials described as an escalation of the 20-month civil war.

"Over the past few days, a handful of Scud missiles were launched inside Syria, directed by the regime against opposition targets. Several landed fairly close to the Turkish border, which is very worrisome," Stavridis wrote.

Syria on Thursday denied it had used Scud missiles in its fight against what it calls "terrorist groups".