Aid agencies have urged all parties to stop the destruction and indiscriminate attacks in the conflict-ridden Syrian city of Aleppo, calling it "one of the most devastating urban conflicts in modern times." Despite this, the United States and Russia are said to be joining forces against militants in Aleppo, according to the RIA news agency. Russian Defence Minister Sergei Shoigu was quoted as saying: "We are now in a very active phase of negotiations with our American colleagues.

"We are moving step by step closer to a plan - and I'm only talking about Aleppo here - that would really allow us to start fighting together to bring peace so that people can return to their homes in this troubled land."

The statement came as rebels in Aleppo reportedly continued to gain ground on forces loyal to the Syrian government and their Russian allies. Aleppo is home to many rebel groups including those thought to be "moderate" by the US, such as the Free Syrian Army. However, other groups such as the al-Qaeda linked Nusra Front, which now calls itself Jabhat Fateh al-Sham, are also active in the city.

Russia says it is targeting "terrorist groups" in Aleppo but many independent sources claim their bombing campaigns deliberately targets hospitals and civilian areas in the Syrian city.

This was denied by Sergei Lavrov, Russia's foreign minister. "We have confirmed our goals to destroy the threats that come from the so-called Islamic State, Nusra and other terrorist organisations and to stop feeding terrorism, which comes from the outside."

Hundreds of people have been killed as fighting intensified over the past few weeks, with tens of thousands trapped and without food, shelter and the basic amenities. According to Reuters, in the rebels' stronghold in the east of the city, an estimated 250,000 people are thought to live.

"No one and nowhere is safe. Shell-fire is constant, with houses, schools and hospitals all in the line of fire. People live in a state of fear. Children have been traumatised. The scale of the suffering is immense," said Peter Maurer, president of the International Committee of the Red Cross (ICRC).

"For four years, the people of Aleppo have been devastated by brutal war, and it is only getting worse for them. This is beyond doubt one of the most devastating urban conflicts in modern times."

Thousands have been forced to leave their homes as the population is at risk from unsafe and untreated water supplies. As emergency measures, the Syrian Arab Red Crescent and the ICRC have begun transporting in drinking water.

"The human cost of the fighting in Aleppo is simply too high. We urge all parties to stop the destruction and indiscriminate attacks, and stop the killing. Parties involved in the fighting need to respect the basic rules of warfare, in order to prevent the loss of more innocent lives. Besides the direct threat posed by the fighting, the lack of essential services such as water and electricity, poses an immediate and dramatic risk for up to two million people, who have great difficulty in accessing basic medical care," said Maurer, according to a news release published by the aid agency on Monday 15 August.

Lavrov claimed that Syrian militants had used temporary ceasefires in the conflict around Aleppo to rearm and regroup. However, Russia's foreign minister acknowledged at a news conference that brief ceasefires did not allow enough time for aid to enter the besieged city and to let civilians leave.