Nasir al-Wuhayshi's group, Al-Qaeda in the Arabian Peninsula, is behind several plots against the United States, including an attempt to blow up a US commercial airliner on Christmas Day 2009, as well as the deadly attack on French magazine Charlie Hebdo in Paris earlier this year.
US officials told The Washington Post they were reviewing intelligence linked to a June 9th drone strike that targeted Wuhayshi, who was also named Al-Qaeda's number two, and other AQAP operatives.
"We are looking to confirm his death," a US intelligence official told the newspaper.
A local Yemeni official told AFP Tuesday that Wuhayshi is believed to have been killed in the raid in Al-Qaeda-held Mukalla, in southeastern Yemen, and that his body could be kept in a local morgue amid tight secrecy imposed by the militants.
"There are currently four bodies belonging to Al-Qaeda members. One of them is believed to be Wuhayshi's," the local official told AFP, requesting anonymity.
Yemen has been wracked by conflict between Iran-backed Shiite rebels and exiled President Abedrabbo Mansour Hadi's internationally recognized government.
Global powers are keen for a speedy resolution of the conflict, fearing the growing power of Al-Qaeda in the Arabian Peninsula, the Yemeni branch of the jihadist network that has taken advantage of the chaos to seize territory.
Meanwhile, the UN has described the country's humanitarian crisis as "catastrophic", with 80 percent of the population — 20 million people — in need of aid.
High-stakes talks were due to continue in Geneva Tuesday to try to end the bloody conflict.
"We do not have a moment to lose," UN Secretary-General Ban Ki-moon said on the first day of talks Monday, adding that the fighting was "giving strength to some of the world's most ruthless terrorist groups".
Ban said the violence had killed more than 2,600 people, half of them civilians.
"Today, Yemen's very existence hangs in the balance," Ban said.
"While parties bicker, Yemen burns . . . the ticking clock is not a time piece, it is a time bomb."
He called for a fresh two-week humanitarian pause to get crucial supplies through, noting that Ramadan — the Muslim holy month of fasting — begins this week.
But analysts said any chance of success at the first talks between the warring factions since Hadi fled Sanaa was "very unlikely".
Yemen expert Laurent Bonnefoy added: "Indeed, each side appears to be inflexible, disinclined toward compromise".
Pre-dawn air strikes meanwhile targeted Huthi rebel positions in the main southern port city of Aden and continued throughout Monday, residents said, as fighting raged on between rebel forces and pro-government fighters.
Rebels fired Katyusha rockets at a residential part of Aden's Mansura district, said Ali al-Ahmedi, spokesman of the pro-government Popular Resistance — a coalition of pro-government fighters, Sunni tribes and
Medics at a nearby hospital said that three members of the same family were killed and four others were wounded in the attack.
AFP could not immediately verify the toll given by Popular Resistance sources of 20 rebels and seven pro-government fighters killed in Aden.
The rebels, supported by military units loyal to ex-president Ali Abdullah Saleh, have seized control of large parts of the country including the capital Sanaa, forcing Hadi to flee to Saudi Arabia in February.
Fearing an Iran-friendly regime on its southern border, Saudi Arabia has been leading a campaign of air strikes against the rebels since March 26th but has so far failed to rout them from territory they have seized.
Yemen Foreign Minister Riad Yassin said the prospects for a breakthrough at the talks in Geneva were poor.
"I'm not very optimistic," Yassin told AFP, adding that the rebels "never respect any treaty".
Yassin likened the rebels to the Islamic State group or Nigeria's Boko Haram and accused them of sending far more representatives and advisors to the Geneva talks than had been agreed.
"They want to come here to make chaos," he said.
The talks began without the presence of the rebel delegation after their UN plane was temporarily delayed in Djibouti.
The UN had worked to get the rebel group to Geneva on time but "there are issues involving international aviation that are beyond the control of the UN", spokesman Stephane Dujarric said.
The government delegation led by the foreign minister reiterated its demands on Sunday night, including that any ceasefire must see the militias withdraw from all territory they have conquered.