Even as the US and other big powers put pressure on Iran over its nuclear programme, which they say is a front for developing a bomb, Saudi Arabia has accused Iranian-backed Shia militias of sectarian killings of Sunni Iraqis.

Saudia Arabia and other Arab governments are also concerned that Shia Iran is gaining influence in Lebanon by supporting Hezbollah in its conflict with the government of Fouad Siniora.

An Iranian official, who did not wish to be identified, said President Mahmoud Ahmadinejad would travel to Saudi Arabia tomorrow, leaving on Sunday, after talks on regional affairs. He gave no other details.

In Riyadh, a Saudi official confirmed that Ahmadinejad would arrive tomorrow and said that he would meet with King Abdullah on Sunday.

Saudi and Iranian officials have met several times to mediate between Lebanese opposition forces led by Hezbollah, which is also backed by Syria, and the Siniora government.

But these talks - as well as Saudi contacts with Washington, and Paris and Iranian talks with Syria - appear to have made little headway.

A Lebanese political source in Beirut said Iran wanted to break the ice between Saudis and Syrians - a key element in defusing Lebanon’s crisis - before an Arab League summit set for Saudi Arabia at the end of March.

Saudi commentators, noting Syrian officials have not visited Saudi Arabia in months, say Riyadh might want a thaw in its relations with Damascus to pry Syria away from Iran.

The Hezbollah-led opposition demands veto power in the Lebanese government and early parliamentary elections. Siniora has refused. Lebanon’s government has no Shia representatives after all Shia ministers quit last November.

The crisis in Lebanon and Sunni-Shia fighting in Iraq has led to fears of growing sectarian divides across the region.

Saudi Arabia, Iran and Syria have all accepted Baghdad’s invitation to attend a regional conference in March on ways of easing tensions in Iraq.

Riyadh’s diplomatic effort to try to limit Iran’s growing regional influence has been led by Prince Bandar bin Sultan.

Western diplomats in Riyadh say he is very close to the US administration but is sometimes an independent operator who does not necessarily represent the king’s thinking.

Iraqi analyst Mustafa Alani, who recently visited Riyadh and met Saudi officials, said Tehran was aware of this and felt it had to woo Saudi leaders, starting with King Abdullah himself.

Ahmadinejad has been to Saudi Arabia on pilgrimage before, but this will be his first official visit.

“The Iranian leadership think they are going to face a major crisis sooner or later with the nuclear programme and the US trying to push them out of Iraq, so basically they want to neutralise Gulf opposition at the least,” Alani said.

“The visit is an Iranian initiative. It wasn’t an invitation. The problem is Ahmadinejad himself. He is not trusted by the Saudi leadership,” he said.

“The Iranians tried to show the Saudis goodwill in Lebanon and that they are open to diplomatic bargaining. They reduced the tension markedly in Lebanon.” – Agencies