Yemen has been embroiled in civil war since early 2015 when Houthi rebels took over the capital of Sanaa and President Abed Rabbo Mansour Hadi fled to the southern city of Aden. Saleh loyalists accused the Houthi fighters of raiding their bases across Sana'a and beyond, an allegation that the Houthi leader has strongly denied.
United Nations spokesman Stephane Dujarric said Cheikh Ahmed called Saleh's killing "an adverse development" which would constitute "a considerable change to the political dynamics in Yemen".
He said the fate of Abull Aziz Bin Habtoor, senior GPC member and prime minister of the Saleh-Houthi alliance's self-declared government, was unknown but that reports suggested the rebels had arrested him.
The commander of Iran's Islamic Revolution Guards Corps, Major General Mohammad Ali Jafari, said Yemen's enemies had been behind Saleh's armed uprising and praised what he called the Houthis' swift quashing of the "coup against the holy warriors", the semi-official Fars news agency reported.
The Houthis' top leader, Abdul-Malek al-Houthi, said Saleh paid the price for his "treason", accusing him of betraying their alliance to side with the Saudi-led coalition.
There was no independent confirmation, but pictures circulated on social media appeared to show Mr Saleh's body. US-backed Saudi coalition forces renewed their attacks on Sanaa in order to back up Saleh's supporters.
- Houthi rebels hold over 40 journalists hostage in Yemen.
The end of the alliance between the Houthis and Saleh might have tilted the three-year civil war in favor of Yemen's internationally recognized government and the Saudi-led coalition.
The conflict has seen civilians repeatedly killed by bombing and through a lack of access to essential food and clean water.
The International Committee of the Red Cross says that as many as 234 people have been killed in Yemen's capital, Sanaa, in street fighting this month between the country's Shiite rebels and the supporters of the slain former president, Ali Abdullah Saleh.
But with Saleh's forces seemingly in disarray, it was not immediately clear if the Saudi-led coalition would be able to turn the split to its advantage.
Global aid groups warned today they were losing the ability to reach civilians in Sanaa.
The bloody conflict has left impoverished Yemen as the world's leading humanitarian disasters with millions of people facing starvation.
The casualty tolls provided by the ICRC are separate from those sustained in airstrikes by the Saudi-led coalition which is waging war on the rebels, known as Houthis.
The Houthis and Saleh's forces began fighting each other in Sanaa last week. Speaking to reporters by phone from Sanaa, he said that "at the same time, people are bracing themselves for more".