Syria is preparing to send fighters to Saudi Arabia to support its escalating conflict with rebels in neighbouring Yemen, three officials with knowledge of the plans have told The Associated Press.

An initial force of about 600 Syrian special forces fighters is expected to be deployed to Saudi Arabia in the coming week, a Syrian official said. The fighters would deploy along the Saudi border and could potentially help Riyadh fight the Iranian-backed Houthi rebels in Yemen.

Syrian military advisers are already in Saudi Arabia, according to a regional official and two Syrian officials, who spoke on condition of anonymity because they were not authorised to comment publicly. No fighters have been sent to Yemen, they said.

One of the officials said Saudi Arabia had insisted the fighters be Syrian nationals, rather than foreign fighters who joined different rebel factions during Syria's civil war. A Syrian delegation led by Khaled Khattab, commander of the 82nd Division, recently made a two-week visit to Saudi Arabia, the official added.

A second Syrian official said 36 Syrian military officials had visited a command and operations room in Jeddah staffed by Saudi and Yemeni officials, where they were briefed on the different front lines and areas of operation. A regional official said Syria had already deployed a small number of advisers to Saudi Arabia, where they have helped train Yemeni forces inside the kingdom.

Damascus has denied that its forces are headed to Yemen. An unnamed diplomatic official dismissed the reports on Saturday, the state-run news agency SANA reported, saying the agreement with Saudi Arabia focuses on training Syrian military forces and building their capabilities. Reuters separately reported that Syria had sent a limited number of military personnel to Saudi Arabia in recent weeks to provide advice and training, citing two Syrian military sources and a senior US official.

The conflicting accounts follow a defence cooperation agreement signed on 4 November during a visit to Riyadh by Syrian President Ahmad al-Sharaa, his second meeting with Crown Prince Mohammed bin Salman in less than a month. During the visit, the Saudi government agreed to lend Syria more than $400 million for postwar reconstruction of homes and basic infrastructure. The detailed provisions of the defence agreement have not been publicly disclosed.

Syria is also discussing joining a joint defence agreement recently signed by Saudi Arabia, Turkey and Pakistan. The Mecca Joint Defense Agreement, signed in August, commits the three countries to regard an attack against one as an attack on all three. Two Syrian officials said a decision had already been made, but not publicly announced, for Syria to join the pact, while the regional official said talks were still going on. One concern, the regional official said, is that Syria might ask the other countries for their support against Israel.

Fighting in Yemen escalated this summer between the Houthi rebels and the government's Saudi-backed forces, and the Houthis have launched direct attacks on Saudi Arabia, including missile strikes on Riyadh. Saudi Arabia has an array of US-supplied fighter jets and missile defences but has been unable to defeat the Houthis in past rounds of conflict, and its other allies have been reluctant to commit ground forces.

Syria, which has a supply of battle-hardened fighters after a long civil war, has so far stayed on the sidelines. President al-Sharaa has said his focus is on rebuilding Syria after its lengthy civil war and that he wants to avoid getting embroiled in new conflicts. He has also turned down proposals by US President Donald Trump for Syrian forces to intervene against the Iran-backed Hezbollah group in Lebanon.

But Saudi Arabia has been key to Syria's reintegration into the Arab world, which had largely shunned Damascus under former President Bashar al-Assad. The Saudis provided funds to Syrian rebels during the civil war and have promised much-needed financial assistance for postwar reconstruction. Syrian involvement in the fighting against the Houthis could also expose it to attacks by militias in neighbouring Iraq that are allied with the Houthis.