At least 150 people have been killed in clashes near Aleppo, a UK-based monitoring group has said, as the UN envoy to Syria said he saw a "glimmer of hope" over a plan to suspend government bombing of the besieged city.

The Syrian Observatory for Human Rights (SOHR) said on Wednesday that at least 80 rebels and 70 pro-government fighters had been killed in clashes over the past 24 hours.

The observatory, which relies on a network of activists on the ground, also said rebels had regained an area north of the city that they lost to government troops the previous day.

The SOHR and Turkey-based activist Bari Abdellatif named the villages as Ratyan and Dweir Zeytoun.

People & Power - Bomb run Aleppo

Syria's state news agency, SANA, reported on Tuesday that the army had seized at least six villages near Aleppo.

The Syrian army, backed by militias, had captured the areas in an attempt to encircle the city and cut off crucial supply lines for the rebels, the agency said.

Aleppo is at the forefront of clashes against the army and is divided into a rebel-controlled west and government-held east.

Wednesday's violence came as the UN special envoy to Syria, Staffan de Mistura, said he had received a Syrian government commitment to suspend airstrikes on the city of Aleppo for six weeks.

"The government of Syria has indicated to me its willingness to halt all aerial bombing ... and artillery shelling for a period of six weeks all over the city of Aleppo from a date which we will be announcing from Damascus," the envoy told reporters after briefing the UN Security Council.

The Syrian military has been accused of using barrel bombs to strike rebel-held areas in the city.

They have been widely criticised because they cannot be precisely targeted, and are believed to have killed thousands of civilians.

Earlier this month, Syria's President Bashar al-Assad denied his forces used barrel bombs.

'Glimmer of hope'

De Mistura said he had "no illusions but a glimmer of hope, bearing in mind that it is our duty to protect civilians wherever we can while we are still hoping to find a political solution".

The envoy said he wanted to see a UN-monitored "freeze zone" that will calm violence there, allow more humanitarian aid access and act as the first step towards a wider solution to the conflict.

Aleppo-based opposition activists have expressed fears that the government would exploit a truce to gather its forces to fight elsewhere, and they have questioned how a ceasefire could work with fighters of the Islamic State of Iraq and the Levant (ISIL) in the area.

The Nusra Front, the al-Qaeda affiliate in Syria, recently dismissed de Mistura's proposal as a conspiracy that would allow Syrian government forces to regroup for more assaults.

De Mistura angered Syrian opposition leaders last week with his comments that Assad remains "part of the solution" in reducing violence in the nearly four-year conflict.

Human rights groups have accused the Syrian government of rounding up tens of thousands of Syrians, many of whom disappear in custody never to be seen again.

In 2013, a UN panel accused Assad's government of committing a crime against humanity by making people systematically vanish.

Since the conflict started in 2011, the UN estimates more than 220,000 people have been killed, nearly 10 million displaced and more than three million forced to flee the country.

Source: Al Jazeera and agencies