The opposition-backed Free Syrian Army (FSA) in Aleppo has rejected a UN truce proposal that seeks to suspend fighting in Syria's second city, a day after the government hinted at considering it. 

Zaher al-Saket, FSA military commander in the city, said on Wednesday that the proposal only serves the regime of President Bashar al-Assad, and pledged that his troops would continue their fight.

"First I would like to say that we completely reject this so-called freeze plan and truce," he said in an interview with Al Jazeera.

"We learned not to trust the Assad regime because they are cunning and only want to buy time. We saw what happened in Homs and we will never accept the same scenario in Aleppo."

The news came as forces loyal to Assad dropped a barrel bomb on Wednesday on Aleppo's al-Marjeh neighbourhood, according to activists.

Images from the aftermath of the reported strike showed men digging through a rubble of a building.

There was no immediate report on casualties from the attack.

Staffan de Mistura,  UN special envoy to Syria, said on Tuesday the Syrian government had responded with "constructive interest" to the UN proposal.

De Mistura set out the plan last month that would allow humanitarian aid through, and will lay the groundwork for peace talks.

As he continues to press for a diplomatic solution, there is no sign of let-up in fighting on the ground.

Syrian state media reported on Wednesday that two rockets were fired at a school in the central province of Hama, killing seven children.

Opposition leader detained

Separately Syrian authorities detained a prominent Damascus-based writer and dissident, Louay Hussein, as he was trying to leave the country at the Syria-Lebanon border bound for Spain.

Hussein is a longtime opposition activist and the leader of Building the Syrian State.

The Britain-based Syrian Observatory for Human Rights also reported on Wednesday Hussein's arrest, saying he was taken to the justice palace in Damascus.

Human rights groups said the government has rounded up tens of thousands of Syrians, many of whom disappear in custody never to be seen again.

A UN panel last year accused Assad's government of committing a crime against humanity by making people systematically vanish.

More than 195,000 people have been killed in Syria since the beginning of the conflict in March 2011, with successive attempts at internationally backed negotiations failing to yield a peace deal.

Nearly 10 million people have been displaced by Syria's civil war, and more than three million have fled the country.

Source: Al Jazeera and agencies