India Tuesday warned of a tit-for-tat action if Britain did not recognise Covishield as a legitimate anti-corona vaccine for its nationals travelling to the UK. Terming Britain's new Covid vaccine policy as "discriminatory", Foreign Secretary Harsh Vardhan Shringla made it clear that India could "take reciprocal measures" if the matter was not resolved at the earliest. "The non-recogition of Covishield is a discriminating policy and impacts our citizens travelling to the UK," Shringla told the media in the Indian capital. "The External Affairs Minister has raised the issue strongly with the new UK foreign secretary. I am told that certain assurances have been given that this issue will be resolved," the Foreign Secretary added. His warning came on a day Indian Foreign Minister S Jaishankar tweeted about raising the issue with his British counterpart Liz Truss on the sidelines of the 76th session of the UN General Assembly in New York. "Pleased to meet new UK Foreign Secretary @trussliz... Urged early resolution of quarantine issue in mutual interest,"  Jaishankar tweeted earlier in the day. As per the new vaccine rules, Indian nationals travelling to the UK will have to undergo self-isolation for 10 days even if they have received both doses of Covishield -- the Oxford-AstraZeneca vaccine produced by the Serum Institute of India.