Supporters' groups have called on Arsenal's board to ensure a substantial portion of its cash reserves of £123m are used to invest in the team, after the club announced a pre-tax profit of £17.8m for the six months to the end of November 2012.

The release of interim results showing the club continued to make a healthy profit on player sales and held cash reserves of £123.3m were criticised by fans' groups who claim they underline the club's lack of ambition.

Continuing the trend of recent years, Arsenal were able to post a profit thanks to the £42.5m recouped from player sales over the summer including those of Robin van Persie to Manchester United and Alex Song to Barcelona, and a modest upside from the property deals that underpinned the move to the Emirates Stadium.

As restive fans face the prospect of an eighth successive season without a trophy, the chairman, Peter Hill-Wood, used his statement to defend the board's approach. "Let me be quite clear that our intention is to keep our best players and recruit new talent to make us stronger," he said. "Although we were disappointed to see Robin van Persie leave the club, we have taken steps to secure our best players and have recently signed Jack Wilshere, Theo Walcott, Kieran Gibbs, Aaron Ramsey, Alex Oxlade-Chamberlain and Carl Jenkinson to long-term contracts."

He also pointed to the acquisitions of Lukas Podolski, Santi Cazorla and Olivier Giroud and the more recent purchase of Nacho Monreal. "Our ability to compete at the top of the game here and in Europe is underpinned by our financial performance which gives the club strength and independence," he said, highlighting the positive impact of new financial regulations introduced by Uefa and the Premier League.

"Our desire is to make everyone connected with Arsenal proud of the club. We know that comes through winning trophies but also through the way we do things and that will remain our constant guide."

Most of Arsenal's revenue growth over the past five years has been driven by the centrally negotiated TV contract, which is due for another major rise next season after the Premier League delivered £5.5bn over three seasons. But Hill-Wood argued that new commercial deals with Emirates, worth "up to £150m", and other new contracts will boost that figure as the original long-term deals that helped bankroll the Emirates are being renewed.

The Arsenal Supporters' Trust called for more investment in the playing squad, again highlighting the club's high ticket prices. "These figures contain few surprises. They show that Arsenal yet again made a profit from the sale of their best players and that the club has large cash reserves," a spokesman said. "Arsenal fans have contributed to this financial health through paying some of the highest ticket prices in world football. A further improvement in the club's financial strength is expected when new TV monies and commercial deals come on stream in 2013 and 2014. AST members want to see this money used for more, and better, investment in the team."

It also criticised the decision-making of the chief executive, Ivan Gazidis, and the manager, Arsène Wenger, questioning whether they were following the right policy in paying relatively high wages across the whole first-team squad but refusing to break the overall structure for specific players.

"The results also show the club does spend considerable money on wages, approximately £150m per annum. But the football decisions made on player investment, player selection and player wage levels are not delivering a more competitive team," said the spokesman.

"The AST believes the club are financially well set to improve on the decline of the last few seasons. The remaining question is whether it has the boardroom leadership and football decision-making expertise to make the money count."