Syrian President Bashar al-Assad has said in an interview for Russian TV he will not quit under foreign pressure, saying the Syrian people must decide.

Western powers and much of the Syrian opposition say it is not conceivable for Mr Assad to lead a post-war Syria.

Mr Assad said Iran was supporting his government "politically, economically and militarily" but denied that Iranian ground forces had been sent.

The latest comments come as Russia increases its presence in Syria.

Mr Assad said that the president "comes to power with the people's assent through elections, and if he leaves, he leaves if the people demand it".

Mr Assad was re-elected in 2014 with 88.7% of the vote. However, the election only took place in government-held areas and the opposition said the vote had no credibility in the midst of a civil war.

'Stop supporting terror'

In the interview Mr Assad also said the refugee crisis which has seen more than four million Syrians flee the country, and millions more internally displaced, was due to "terrorism".

He urged Western countries to "stop supporting terrorists" if they are concerned about an influx of refugees.

Mr Assad's message is not new, says the BBC's Sebastian Usher. From the first days of the Syrian crisis, when he was facing unarmed opposition from street protests, he has framed it as a battle against terrorism,

What has changed is the timing and the circumstances. Mr Assad and one of his main backers, Russia, are pointing to the refugee crisis and the rise of Islamic State (IS) as proof that their stance has been correct, our correspondent adds.

This satellite image - taken on 4 September 2015 - allegedly shows construction at Latakia's airport

Russia sends signal over future role

On Tuesday US Secretary of State John Kerry called his Russian counterpart Sergei Lavrov in an attempt to clarify the reason behind Moscow's military build-up in Syria.

Mr Kerry warned that continued support for President Assad "risks exacerbating and extending the conflict", a statement said.

Russia says it is helping Syria fight Islamic State militants.

Moscow has increased its presence in the country just as the regime is losing ground to rebel groups.

Russian President Vladimir Putin has pledged continued military support for President Assad and has urged other countries to join Russia in sending "military-technical assistance".

A Pentagon spokesman said on Monday that a steady flow of people and equipment near the north-western city of Latakia suggested Moscow was planning to establish a "forward air operating base" at an airport there.

Last week, officials in Washington quoted by Reuters said Moscow had sent more aircraft and two tank landing ships to Russia's naval base in the Syrian coastal city of Tartus.