WASHINGTON, Aug 23 (Reuters) - Leaders of G7 advanced economies are expected to pledge unity on whether or not to officially recognise or sanction the Taliban when they meet virtually to discuss Afghanistan on Tuesday (Aug 24), according to two diplomatic sources.

US allies are still smarting from Washington's delays in outreach after Kabul fell on Aug 15, and foreign diplomats in Washington said cooperation will be a key theme of the call.

"The G7 leaders will agree to coordinate on if or when to recognise the Taliban," said one European diplomat. "And they will commit to continue to work closely together."

The Taliban's lightning-fast takeover of the country this month, after US troops started to withdraw and President Ashraf Ghani fled, left foreign governments scrambling and sparked a panicked mass exodus from the country.

Leaders of the United States, Britain, Italy, France, Germany, Canada, and Japan may use the possibility of unified official recognition, or renewed sanctions to push the Taliban to comply with pledges to respect women's rights and international relations.

British Prime Minister Boris Johnson will stress a unified approach during the G7 talks, which will also include NATO Secretary General Jen Stoltenberg and UN Secretary General Antonio Guterres, said Karen Pierce, Britain's envoy to the United States.

Recognition is a political act taken by sovereign states with important consequences, including allowing the Taliban access to the foreign aid relied upon by previous Afghan governments. A 2020 agreement signed by the former Trump administration explicitly states that the group "is not recognised by the United States as a state."

G7 leaders will also discuss a possible extension of Biden's Aug 31 deadline for withdrawing US forces, to give the United States and other countries more time to locate and evacuate Western citizens, Afghans who aided NATO and US forces and other vulnerable people, the sources said.

Britain and France are pressing for more time, but a Taliban official said foreign forces had not sought an extension and it would not be granted if they did.

G7 leaders will also commit to coordinate on any sanctions and resettlement of a wave of refugees, the sources said.

The G7 will take stock of the current evacuation efforts and commit to coordinating closely on further steps, including security, humanitarian assistance and resettlement of refugees, Pierce said.