MOSCOW (Reuters) - Syrian President Bashar al-Assad flew into Moscow on Tuesday (Oct 20) for a meeting with Russian President Vladimir Putin, during which the two men discussed their joint military campaign against Islamist militants in Syria, a Kremlin spokesman said.

"The President of the Syrian Arab Republic Bashar Assad came on a working visit to Moscow yesterday evening and held talks with Russian President Vladimir Putin," the spokesman, Mr Dmitry Peskov, told reporters.

The Kremlin made the details of the visit public a day later, on Wednesday. It did not say whether the Syrian leader was still in Moscow or had returned home.

The visit is believed to be Assad's first foreign trip since the outbreak of the Syrian crisis in 2011 and comes three weeks after Russia launched a campaign of air strikes against Islamist militants in Syria on September 30.

"First of all I wanted to express my huge gratitude to the whole leadership of the Russian Federation for the help they are giving Syria," Assad told Putin, according to a Kremlin transcript. "If it was not for your actions and your decisions the terrorism which is spreading in the region would have swallowed up a much greater area and spread over an even greater area."

Putin hailed the Syrian people for standing up to the militants "almost on their own," saying the Syrian army had notched up serious battle field success in recent times.