Though there was no clear breakthrough on Thursday, when the initial deal was supposed to expire, the UN cited "promising" signals for maintaining a truce that has lessened suffering in war-torn Yemen, according to the international body.

Aid agencies and Western governments have pushed the parties concerned to extend the ceasefire, which has dramatically decreased the intensity of fighting in a conflict described by the UN as the world's worst humanitarian crisis.

"We have received preliminary, positive indications from the parties at this point," Stephane Dujarric, spokesman for UN chief Antonio Guterres, told a press briefing Wednesday. 

But he did not elaborate, saying only that "as soon as we have something more concrete, we will share with you."

Read next: Al-Mashat: If aggression does not abide by truce, Yemeni forces ready

Yemen has been under war led by the Saudis for 8 years now. A UN-brokered truce went into force in April but was repeatedly violated by the Saudi-led coalition. 

On Wednesday, the first commercial flight between the two cities since 2016 took off from Sanaa, following weeks of Saudi stalling and hindrance. It is the seventh such trip since the ceasefire, with the last six all flying to Jordan's capital, Amman.

Aside from the flights, which provide a lifeline for Yemenis seeking medical treatment in other countries, the truce has allowed oil tankers to dock in the port of Al-Hudaydah, potentially alleviating fuel shortages in Sanaa and elsewhere.

Read next: Guterres hopes Yemen truce will inspire "political process" for peace

According to Dujarric, more than four million people have been displaced by the fighting, and 19 million will be hungry this year. That includes "more than 160,000 who will face famine-like conditions," he said.