London’s Heathrow airport has said a new £10 charge for visa-exempt passengers travelling through the hub is a “huge blow,” despite reporting a second consecutive month of record passenger traffic.

Some 6.7m passengers passed through the hub in March, up eight percent from the previous year and bringing the year-to-date figure to 18.5m.

North American and European Union and trips made up the lion share of the total, at 1.6m and 2.1m respectively. Trips to the Asia Pacific region soared 18 per cent to 892,000.

But Heathrow’s chief executive Thomas Woldbye called on the government to “exempt airside transit passengers from the ETA scheme to avoid encouraging passengers to spend and do business elsewhere.”

The new so-called Electronic Travel Authorisation (ETA) means passengers arriving in Britain from certain countries will have to pay a £10 fee and wait up to three days for an online permit – even when travelling via connecting flights.

It is controversial among airlines and airports as connecting passengers not passing through border control will still need the permit, making the UK an outlier compared with other countries.

The ETA was first introduced for Qatari nationals in November. Heathrow, which operates far more connecting flights than any other UK hub, said it had seen 19,000 fewer Qatari passengers pass through since then.

Bahrain, Kuwait, Oman, the United Arab Emirates, Saudi Arabia, and Jordan were added on 1 February, and the Home Office is planning to roll it out across the board.