Iran's Hassan Rouhani was expected in Pakistan on Friday in a landmark visit, his first since becoming president, at a time when Saudi Arabia is courting Islamabad to increase participation in a new Saudi-led military alliance of mostly Sunni nations, a coalition perceived by Tehran as an anti-Shia block.

Pakistan, a majority Sunni country, has traditionally close ties with Saudi Arabia, which is hostile to Iran, a Shia power. The kingdom accuses Tehran of supporting Shia Houthi rebels in Yemen against the internationally recognized president, Abd Rabbo Mansour Hadi.

Saudi Arabia has been leading a coalition of mostly Gulf Arab states in a blistering air-campaign against the Houthis in the conflict in Yemen, widely seen as a proxy Saudi-Iran war.

Last year, Pakistan refused a Saudi request to send troops into Yemen after a vote in Parliament delivered an overwhelming "no." Prime Minister Nawaz Sharif in a January visited the kingdom, expressing support for the alliance but without making any military commitment. Local Pakistani papers have carried unconfirmed reports that Saudi Arabia asked Pakistan's military chief, Raheel Sharif, to head the alliance.

Rouhani's visit is also a landmark moment for Iran, after international sanctions in the wake of the nuclear deal between Iran and world powers.

"This visit means a lot," said Imtiaz Gul, executive director of the Islamabad-based Center for Research and Security Studies, adding that Pakistan is still "ambivalent" about its participation in the new Saudi-led alliance.

Pakistan, a Muslim-majority country of 180 million, has a Shia minority that makes up about 15 percent of the population.

The country frequently sees Sunni militant groups attacking the Shia minority, which in turn has accused Saudi Arabia of financing groups like Lashkar-e-Jhangvi, blamed for many such deadly attacks. For their part, the militant Sunni groups accuse Iran of financing a Pakistani militant Shia group, Tehreek Nafaz-e-Fiqh-e-Jafariya.

Rouhani's visit is also expected to discuss a controversial gas pipeline from Iran, through Pakistan to India. Work has stalled on the Iran-Pakistan section, which was designed to help Pakistan meet its energy needs. Iran has invested over $2 billion in the project, but Pakistan has yet to finish construction on its half of the pipeline.

Washington had for years opposed the project amid concerns over Tehran's nuclear program.