Pentagon welcomes Saudi offer to send troops to Syria

US Defence Secretary Ash Carter has welcomed a Saudi offer to participate in ground operations against Islamic State group fighters in Syria.

A Saudi military spokesman said the kingdom was ready to commit ground troops, if the US-led coalition were to agree.

Increased activity by other countries will make it easier for the US to accelerate its fight against IS, said Carter on Thursday night.

"That kind of news is very welcome," Carter told reporters during a visit to a US Air Force Base in Nevada.

While reports of US coalition-led ground incursions have circulated since the onset of airstrikes against IS group militants in late 2014, recent developments indicate increasing preparations for an all-out assault.

Riyadh's offer and its tacit acceptance by the US are key indicators of increasing efforts by the US-led coalition of reasserting agency over the Syrian civil war, following the Russian intervention.

One of the first Arab states to join the anti-IS coalition in September 2014, Saudi Arabia has participated in airstrikes on targets in Syria against IS militants, who have seized large parts of Syria and Iraq.

But this will be the first time its troops will be deployed on the ground in Syria.

"The kingdom is ready to participate in any ground operations that the coalition may agree to carry out in Syria," said military spokesman Brigadier General Ahmed al-Asiri on Thursday.

"If there was a consensus from the leadership of the coalition, the kingdom is willing to participate in these efforts, because we believe that aerial operations are not the ideal solution and there must be a twin mix of aerial and ground operations," Asiri added during an interview with al-Arabiya TV.

Riyadh already has troops deployed in Yemen, in a fight against Iranian-backed Houthi rebels.

But fresh "progress" in that war means troops can now be freed up to redeploy in Syria, Asiri said.

Despite recent strains with Washington following the nuclear deal with Iran, Saudi Arabia has frequently shown willing to fight against IS with the US-led coalition.

Riyadh's proposal is expected to be discussed at a summit of defence ministers of coalition countries in Brussels next week.