Arsenal's chief executive, Ivan Gazidis, has warned that "ordinary fans are increasingly being priced out of live football", even as his club faces a backlash over season-ticket price increases of 6.5%.

The cheapest season ticket at the Emirates will cost £951 next season, leading supporters' groups to warn that some fans face being priced out of the ground at a time when uncertainty also surrounds the intentions of the club's new owner, the American Stan Kroenke.

In a letter to the Arsenal Supporters' Trust (AST), Gazidis argues that prices have been held flat since the move to the Emirates and says the increase includes the 2.5% VAT rise levied by the government.

But he added: "I share your concerns that ordinary fans are being increasingly priced out of live football. This is bad for the continued health of the game and is driven primarily by escalating and ultimately unsustainable levels of spending on transfer fees and player salaries."

Arsenal's most recent accounts warned that it faced further escalation in the inflation of players' salaries, while the club is also more reliant on matchday income than rivals because its commercial income lags behind due to the need to sign long-term deals to underwrite the move to the Emirates.

"This is a fundamental issue that football needs to address and is why I have been a vocal supporter of Uefa's proposals to bring more restraint and responsibility to spending within football," the Arsenal chief executive said.

Gazidis promised a wholesale review of the entire ticket pricing structure at the Emirates, already one of the most expensive stadiums in Europe, in time for the 2012-13 season.

"The AST is very disappointed that Arsenal have rejected our call for ticket prices to be frozen. This decision will sadly see some loyal fans priced out of the Emirates," it said in a statement.

"Now that this decision has been made, Arsenal supporters will expect to see the extra income raised invested in team strengthening. It would be shocking to see this money end up being extracted from the club by Stan Kroenke. The AST believes Kroenke should issue further reassurance to supporters ahead of them renewing their season tickets that this is the case."

Manchester United has also written to season ticket holders to inform them that prices will rise by the equivalent of £1 per match next season, a rise of between 2% and 3.7%.

The club has said that the rise is a result of the 2.5% VAT increase and other increased costs, including player wages and utility bills, have not been passed on to fans. It has also introduced a new tier of tickets for 16- to 17-year-olds.

The Manchester United Supporters Trust (MUST) recently called on the Glazers to mirror the price cuts at their NFL franchise, the Tampa Bay Buccaneers, where prices were recently reduced by up to 30%. More than 28,000 fans emailed Joel Glazer to call for a price cut.

Opponents of the Glazers have consistently argued that the US owners have raised ticket prices at Old Trafford while sucking an estimated £450m out of the club in interest charges and debt-related payments. The new price increases are likely to lead to a new PR battle over the Glazers and their impact on the club.

Andy Green, who blogs on Manchester United's finances under the name Andersred, has calculated that ticket prices have risen by an average of 55% since the Glazers bought the club in 2004‑05. Prices rose regularly until last season, when they were frozen in the wake of the green and gold campaign.

But club insiders argue that the average annual increase of 5.79% in the five years since the Glazers bought United is lower than average annual increase in the preceding five years (when it was 5.85%).

The MUST chief executive, Duncan Drasdo, said that the claim was "laughable" because the calculation wrongly ascribed the first 10.6% rise of the Glazer regime to the previous PLC ownership – a rise that was linked at the time to the takeover speculation surrounding the club and could have been reversed by the new owners.

"Fans have seen prices rise 55% in the seasons since the Glazers took over and at a time when the club has been enjoying continued commercial success – something they seem more than happy to crow about – along with more than £100m in the bank sitting unspent, they want to take yet more from ordinary supporters many of whom are struggling in difficult economic conditions," he said.