Last updated on .From the section Football

Celtic sold Virgil van Dijk (left) shortly after their Champions League play-off defeat by Malmo

Celtic have announced a pre-tax profit of £11.7m in their interim results.

The figure for the six months to 31 December is an increase of £5.1m from 2014, helped in part by the £13m sale of Virgil van Dijk to Southampton.

Revenue is up 0.3% to £31.4m but the club expect a dip in the coming months with no further European matches this season and fewer home games.

"Our performance in Europe this season has been the cause of considerable frustration," said chair Ian Bankier.

The Scottish Premiership leaders have increased investment in their playing squad, spending £6.1m on Scott Allan, Logan Bailly, Carlton Cole, Ryan Christie, Nadir Ciftci, Saidy Janko and Jozo Simunovic last summer.

Bankier has highlighted the challenge of maintaining "a settled and winning squad" during European qualifers

Subsequently, during the 2016 January transfer window, they added Danish defender Erik Sviatchenko and Turkish striker Colin Kazim-Richards while English forward Patrick Roberts joined on loan from Manchester City for 18 months.

After exiting the Champions League at the play-off stage at the hands of Malmo and going into the Europa League, Ronny Deila's side finished bottom of their group with no wins and three draws.

Their hopes of retaining the Scottish League Cup were ended by Ross County in last month's semi-final but they are still in the Scottish Cup.

In the league, they lead Aberdeen on goal difference but the Dons have played a game more.

"The strategy of the board is unchanged," added Bankier in his statement.

"Our overwhelming priority is to win the SPFL Premiership and to qualify for the group stages of the Uefa Champions League.

"The challenge has been to maintain a settled and winning squad throughout the summer months when the crucial Champions League qualifying matches are played, to manage the player changes during the summer transfer window and then to kick on when the new season begins.

"Each season we meet this challenge within the financial constraints of where we sit in Scottish football, for to do otherwise would be reckless."