UK defence minister wants Raqqa offensive 'in weeks'
Fallon's comments were made as he arrived for a two-day NATO defence ministers' meeting in Brussels.
"We hope a similar operation will begin towards Raqqa in the next few weeks," he said.
At present, Iraqi government forces backed by loyalist militias and an international coalition are engaged in an offensive to capture the IS-held city of Mosul in Iraq.
The expected capture of Mosul will set the spotlight on Raqqa as the militants' last key stronghold.
On Tuesday, US Defence Secretary Ashton Carter said that the US-led coalition is "laying the groundwork" for an offensive on Raqqa.
"We have already begun laying the groundwork for our partners to commence the isolation of Raqqa," Carter said after meeting coalition defence ministers in Paris to discuss the aftermath of the planned capture of Mosul.
"Today we resolved to follow through with that same sense of urgency and focus on enveloping and collapsing ISIL's control of Raqqa," he added, using another acronym for IS.
Mosul and Raqqa are IS's two main strongholds, acting as the capitals of their so-called caliphate and providing a source of revenue and territory.