A projectile has struck a passenger terminal at the international airport in Riyadh, a day after a missile hit the same terminal and killed 12 people, the Saudi-led coalition fighting Iran-backed Houthi rebels in Yemen said.
The Houthis claimed responsibility for those attacks and others.
Saudi authorities said there were injuries in the latest attack on the King Khalid International Airport complex for terminals 3 and 4 for domestic flights.
Saturday's missile attack was the deadliest in a Gulf Arab nation since the Iran war began, with another 300 people wounded, some critically. The airport was still closed Sunday.
The sharp escalation in the new front in the war threatens to draw in greater US military involvement, as President Donald Trump has said he is weighing joining the fight against the Houthis. There was no immediate White House comment on Sunday.
India's embassy in Saudi Arabia said one of its citizens died Sunday of injuries sustained in Saturday's attack, which would bring the toll to 13.
The latest strike in Riyadh came shortly after the Houthis said the airport in the rebel-held Yemeni capital of Sanaa had been struck again, and blamed the Saudis.
At stake in this escalation are global supplies and prices of oil as well as commercial shipping through a crucial alternative waterway to the Iran-threatened Strait of Hormuz - along with civilians and aviation throughout the region.
Trump on Saturday also said he planned to speak with Saudi Crown Prince Mohammed bin Salman, who has been seeking assistance.
A US intervention could prompt the Houthis to halt shipping through the Bab el-Mandeb Strait at the southern end of the Red Sea off Yemen and further restrict the flow of oil out of the Persian Gulf. The rebels seized key areas along the strait last month and the Saudi-led coalition has been trying to seize them back.
Saudi Arabia is running low on missile interceptors and has asked France, Britain, Pakistan and Egypt to deploy air defence support to the region, regional officials told The Associated Press last month, with one noting that the US has seen its own stock dwindle during the war with Iran.
Sunday's attack occurred as the Saudis hosted a major international energy conference in Riyadh, with other high-profile events including an investment gathering on the horizon. Saudi Arabia under Crown Prince Mohammed bin Salman has sought to open more to the world as a business and tourism destination, but the Houthi attacks threaten those efforts.
"There is no way that somebody will break our back. We are like a phoenix, we come out of the ashes all the time," the Saudi energy minister, Prince Abdulaziz bin Salman Al Saud, told the conference.
He added that the kingdom is also working on pipelines in addition to the East-West one that was attacked and closed for days last month, with no details.
Earlier Sunday, the Houthi-run health ministry said a child was killed and six people wounded in a suspected Saudi air strike on a house in Sanaa. The ministry also said 91 Yemenis have been killed by the Saudi-led coalition in five weeks, 60 per cent of them women and children.
There was no immediate comment from Saudi authorities on the claims.
On Sunday, the Houthis also claimed attacks on King Fahd Airport in the city of Damma, as well as oil and gas facilities in the kingdom's east. They have targeted the Riyadh airport, which has no military facilities, every day since Wednesday.
The rebels again warned "all airlines, experts, employees, workers and travelers against using Saudi airports and airspace, as they are vulnerable to attack and have become a theatre of operations for our forces."
Several international airlines have suspended flights for varying periods.
Saudi authorities said the dead in Saturday's attack included four Saudi citizens, two Bangladeshi nationals, a Palestinian, a US citizen, an Egyptian, a Jordanian, a Syrian and a Sudanese.
Until recently, the Houthis had been largely on the Iran war's sidelines, but they have developed their military capabilities in recent years to become one of Tehran's most powerful allies. Now, they are helping Iran to pressure a key US ally.