Boris Johnson faced claims his system for international travel is in “chaos” after proposals for a new “amber watchlist” category were abandoned.

The Prime Minister pledged to keep travel rules during the pandemic as simple as possible and senior sources ruled out the prospect of a new category.

Meanwhile, it has emerged the head of the Joint Biosecurity Centre (JBC), which advises on the travel rules, has quietly left her post without a successor being appointed.

The Government had been considering the new watchlist for nations at risk of being moved into the red group which requires hotel quarantine on return for 10 days at a cost of £1,750 for an adult.

But following a backlash by Tory MPs, ministerial concerns and complaints from the travel industry, Government sources confirmed there would be “no amber watchlist”.

Government minister Gillian Keegan told Times Radio: “We have explored all options, looked at all options, but the most important thing is that the system is actually simple enough for people to understand.”

The skills minister acknowledged “there was a lot of discussion about these kind of different categories potentially being more complex and more difficult for people to navigate”.

Travel expert Paul Charles, director of The PC Agency consultancy, said he expected further changes to the rules, claiming “high level” sources had told him the “amber plus” and “green watchlist” categories would also be dropped.

“There needs to be more simplicity and a reduced testing regime,” he said.

Shadow transport secretary Jim McMahon demanded the data behind the Government’s decisions on travel rules.

“The Tories are in total chaos over their border policy, with days of confusion surrounding their plans for an amber watchlist,” he said.

“Not only have ministers failed to protect our borders, allowing the Delta variant to reach the UK in such force, but time and time again they’ve refused to be straight with the public and industry to provide them with the information they need to build confidence, with clear information on the direction of travel of infections in each country.

“Ministers need to get a grip and set out a proper strategy, provide full data and progress work with global partners on international vaccine passports so travellers and the industry can have the maximum clarity, instead of reckless​ U-turns and confusion.”

Ms Keegan also confirmed that Clare Gardiner had left her role as director general of the JBC.

The Guardian reported that her details were removed from the JBC’s website in mid-June.

Asked on LBC to confirm if Dr Gardiner has resigned, Ms Keegan said: “Yes I believe that she has.

“I mean I don’t have any responsibility for that area, but you know, all of these things – there is a group of experts who are basically there that are looking at data, analysing data and then giving advice to the Government, and so I guess they will be looking for a new chair.”

On Sky News Ms Keegan rejected the suggestion the JBC had been left rudderless by Dr Gardiner’s departure because “there’s still a team of experts” who are “looking at the data and giving their analysis based on that”.

In other developments, Nicola Sturgeon is due to announce whether most remaining coronavirus restrictions in Scotland will be lifted on Monday August 9 as planned.

The Scottish First Minister set the date in June, even before the move to Level 0 on July 19 which increased the numbers of people who could gather and extended the opening hours of hospitality.

Other businesses such as soft play were finally allowed to reopen, however nightclubs are among those still closed ahead of Tuesday’s statement in a virtual session of the Scottish Parliament.

Sports stadia and concert venues may go back to being able to welcome full capacity crowds again for the first time in nearly 18 months if changes are approved.