Britain’s Foreign Secretary, Philip Hammond said on Wednesday that Russia must confirm its air strikes targeted ISIS and Al Qaeda affiliates in Syria.
"It's very important that Russia is able to confirm ... that the military action it has undertaken in Syria this morning is directed at ISIL [ISIS] and Al Qaeda affiliated targets only and not at moderate opponents of the Assad regime," Hammond told the UN Security Council.
"Actions in support of the (Syrian) regime are incompatible with the effective prosecution of the war against ISIL [ISIS] in Syria," he said.
Russian Defence Ministry said their jets targeted ISIS, as US officials said it does not appear that the Russian air strikes are targeting ISIS held areas.
Meanwhile, Britain’s Prime Minister, David Cameron said if Russia’s attack was conducted to support Syrian President, Bashar al Assad it would be a “retrograde step”.
"We'll need to look very carefully at the reports and exactly what has happened,” he said during his visit to Jamaica.
"I have a clear view, which is that if this is part of international action against ISIL and that appalling terrorist death cult outfit, then that is all to the good."
Hammond had earlier said the United Kingdom would keep targeting ISIS for “as long as it takes”.
At the UK’s national speech to the General Assembly, Hammond said the people of Syria were dealing with “twin evils” of ISIS and “murderous regime” of Assad. He called for world leaders gethered in New York to work together to “crush” ISIS.
"We share a responsibility to act to end the bloody civil war and create an inclusive political process, and to work together to crush IS and banish its ideology from the face of the earth," he said.
"The UK will continue to be a leading member of the international coalition against Isil, including carrying out more air strikes in Iraq than any other country except the US, for as long as it takes to prevail in what will ultimately be a generational struggle against the Islamist extremist ideology that drives it."
Early on September, Cameron declared the UK had conducted its first drone attack against one of its own citizens in Syria.
In 2013, the House of Commons had voted against UK military action in Syria. However, last September, it upheld British participation in air strikes against ISIS targets in Iraq.
Cameron also pointed out the need to provide sanctuary to the Syrian refugees.
"It is incumbent upon all of us to support them as they bear that burden; to ensure that the UN appeals for Syria are fully funded,” he said.
"And I am proud that the UK is making the second largest contribution of any country to the humanitarian mission in the region."
The UK has declared that it would take in 20,000 Syrian refugees by 2020.