India is evacuating its nationals from Afghanistan on a "special flight" from Mazar-i-Sharif - the country's fourth-largest city as the Taliban launch another offensive.

"A special flight is leaving from Mazar-e-Sharif to New Delhi. Any Indian nationals in and around Mazar-e-Sharif are requested to leave for India in the special flight scheduled to depart late today evening," the Indian consulate in Mazar-e-Sharif tweeted.