The government has defended minister Alok Sharma, who has reportedly visited more than 30 countries without quarantining on his return.
The Daily Mail reported that he visited seven red list countries in his role as president of the COP26 climate conference, taking place in November.
He then used an exemption available to ministers to not have to quarantine when returning to the UK.
A government spokesman said his meetings were “crucial” ahead of COP26.
And they said all ministers were subject to the same rules on quarantine and testing.
But Labour’s shadow justice secretary, David Lammy, told Sky News it was “one rule for them, another for us”.
The Daily Mail also claimed Mr Sharma held a meeting with Prince Charles days after returning from Bangladesh – a red list country – before going on a visit to a primary school.
The meeting with the prince was held indoors and without masks.
Mr Sharma left his post as business secretary in January to take over the presidency of COP26 – the United Nations Climate Chance Conference due to take place in Glasgow later this year.
Since then he has met with dignitaries across the globe to discuss climate commitments ahead of the conference, despite the ongoing pandemic.
Asked by the BBC’s Nick Robinson in June how he defended his air travel when he is leading on environmental policy, he said it was “really important” to meet other governments to discuss plans and the visits had been “targeted”.
But he is now facing further criticism for not quarantining on his return from the trips, including from red list countries such as Bangladesh and Turkey.
Exemption for ministers
UK citizens are advised not to travel to red list countries “except in the most extreme of circumstances”.
But if they do, they are required by law to quarantine in a government-approved hotel for 10 days at a cost of £2,285 for one adult.
Breaking this law can result in a fine of up to £10,000.
However, so-called “Crown servants” – or government ministers – are exempt from this rule if they travel to carry out “essential government work”.
Asked about the criticism, a government spokesman said: “Helping the world tackle the climate emergency is an international priority for the government.
“Virtual meetings play a large part, however face-to-face meetings are key to success in the climate negotiations the UK is leading as hosts of COP26 and are crucial to understanding first-hand the opportunities and challenges other countries are facing in the fight against climate change.”
Mr Sharma is currently in Brazil and has tweeted that he is having “constructive meetings”.