The UK aviation regulator has partly rejected plans by Heathrow to significantly raise its landing fees to fund a multibillion-pound upgrade, arguing the airport can still invest without steep rises to ticket prices.

The Civil Aviation Authority said the average charge for each passenger should rise from £28.40 to £28.80 between 2027 and 2031.

Last year, Heathrow proposed a 17% increase to £33.26, which resulted in criticism from airlines who said it would lead to higher ticket prices for passengers.

The CAA said its average passenger charge would instead rise by 1%. That increase is £5.40, or 16%, lower than the changes proposed by Heathrow but significantly higher – £5.80 or 25% – than the changes wanted by the airlines.

Selina Chadha, the group director of consumer markets at the CAA, said: “Our primary duty is to protect consumers and at the heart of today’s proposals is doing the right thing for passengers using Heathrow airport, while supporting sustainable growth, investment and efficiency.

“Our proposals for the airport charges levied by Heathrow on airlines strike the right balance between keeping passenger prices fair, while enabling the airport to make the investment needed to improve services for the future.”

In its initial plans published on Tuesday, the CAA proposed Heathrow spend between £5.4bn and £6.1bn on projects including upgrading the airport’s electrical system. Last year, Heathrow was forced to close after a fire at a nearby electricity substation caused a power cut, resulting in the cancellation of more than 1,300 flights.

Europe’s busiest airport had been seeking approval to spend up to £10bn to handle an extra 10 million passengers a year by 2031, with upgrades including a plan to modernise Terminal 5.

Thomas Woldbye, the chief executive of Heathrow, said: “We will now review the CAA’s initial proposal in detail to fully understand the implications for delivering the innovation, progress and improvements customers expect.

“On the face of it, the CAA’s proposal may force choices that create trade-offs for service and delay delivery.”

British Airways’ owner International Airlines Group (IAG), the biggest operator at Heathrow, said that the rise in charges would mean passengers paying for “exorbitant” returns to the airport’s shareholders, led by the French private equity group Ardian and Middle Eastern sovereign wealth funds.

An IAG spokesperson said: “Heathrow is already the most expensive hub airport in the world, and we’re frustrated with these initial proposals for the next five years that sees [it] overcompensated [and] passengers fund exorbitant investor returns.”

They said the charges would be in addition to the proposed £49bn for a third runway and urged the CAA to consider the airline’s alternative business plan and curtail Heathrow’s “excessive spending regime”.

The CAA will publish its final proposals in November, which do not include its plans for a third runway, with a final decision expected in April 2027.

In 2023, Heathrow was forced to cut passenger charges by almost a fifth after losing an appeal to the UK competition watchdog against the CAA.