Several Saudi-led warplanes were spotted by local residents flying over Sanaa early on Wednesday, marking the first clearly breach to a UN-backed fragile truce announced a day before.
The sound of warplanes, which fly over for about 15 minutes, could be clearly heard by all residents, many of them reported they spotted several jets at the same time, Xinhua reported.
There was no response from anti-warplane weapons, which are under control of the Shia Houthi rebel group.
Houthi official Hamid al-Bukhaity said his group will not fire at the warplanes, rather it will observe the truce.
Meanwhile, officials and residents of the southwestern province of Taiz accused Houthi fighters of killing seven residents and wounding nine others in shelling that they said has been sporadically continued since the truce took effect Tuesday midday until Wednesday morning.
The officials and witnesses confirmed that Houthi militias are still besieging Taiz despite the truce, preventing water and medical supplies from entering the region. There was no immediate comment from the Houthi group.
Witnesses and observers in Taiz said the Houthi shelling was responded by the pro-government forces.
Also on Wednesday morning, officials and villagers of al-Mazarik district of the northeast province of al-Jouf said Houthi militia fired tank and artillery weapons on the district as they are advancing to near a government-controlled military camp, al-Nasr, in an apparent attempt to retake it.
They said the government forces fired back to repel the advancing rebels.
On Tuesday evening, military sources said that Houthi rebels and government loyalists in the country's northern province of Marib traded clashes 50 minutes after the beginning of the truce.
The clashes also erupted between the warring forces in Taiz, causing casualties among civilians in the area, according to local residents.
The fighting also raged in southern province of Lahj near Taiz on Tuesday afternoon, according to local sources.
The seven-day ceasefire went into effect on Tuesday afternoon between the Saudi-backed Yemeni government forces and the armed rebels of the Shia Houthi group across the country's war-torn provinces.
The ceasefire coincides with the kick-off of UN-sponsored peace talks in Switzerland between the two warring sides.
Yemen's official news agency reported the internationally recognised Yemeni President Abd Rabbu Mansour Hadi has requested the command of the Saudi-led coalition to abide by the ceasefire and halt military air bombings on Houthis.
Hadi declared last week that the seven-day humanitarian cease-fire will be extended if the Shiite Houthis and their allies lift siege on Taiz, free detainees and end military actions.
In Geneva, the warring parties began the talks facilitated by UN Special Envoy for Yemen Ismail Ould Cheikh Ahmed.
The talks involved 24 Yemeni representatives and advisors in the negotiation for a permanent and comprehensive ceasefire, an improved humanitarian situation and the return to a peaceful and orderly political transition.
The Saudi-led Arab coalition has been backing Hadi's government by fighting the rebels since March this year, and later sent in thousands of ground troops from the UAE, Sudan, Qatar and other nationalities to retake five southern provinces from Houthi militias.
The Shia Houthi rebels, supported by the Republican Guard Forces loyal to former president Ali Abdullah Saleh, are still holding the capital Sanaa and most of the northern part of the country since September last year.
More than 6,000 people have been killed in Yemen since March in ground battles and airstrikes, half of them civilians.
