Tui pinned the latest round of cancellations on the "ongoing political and economic instability" in the country.
The Foreign Office continues to advise against all but essential travel to Sri Lanka following months of political turmoil.
All Tui holidays to Sri Lanka departing up to and on 31 August have now been cancelled, the airline and operator said on Wednesday (10 August). The programme had previously been suspended until 22 August.
"We will be proactively contacting all impacted customers in departure date order to discuss their options," said Tui in a statement. "Please note this advice does not apply to customers transiting through Sri Lanka’s international airport.
"We will continue to monitor the situation and update customers should there be any further updates. We would like to thank our customers for their understanding at this time."
The FCDO strengthened its advice to advise against all but essential travel to Sri Lanka in May, prompting Tui to suspend its programme.
This advice was relaxed in mid-June, only for it to be reinstated at the start of July.
The FCDO’s main concern is around the supply of the basic necessities, such as fuel and food.
