Celtic completed the loan signing of Ghana winger Wakaso Mubarak on a day in which their transfer policy came under fire following their failure to qualify for the Champions League.

The 24-year-old, who played at the World Cup finals, arrives on a one-year loan deal with Celtic having the option to buy the player from Russian side Rubin Kazan.

He is Ronny Deila’s fifth signing of the summer but Celtic have still to pay a transfer fee since Neil Lennon quit as manager.

Free agent Craig Gordon was Deila’s first signing before Cardiff forward Jo Inge Berget, Manchester City defender Jason Denayer and Aston Villa winger Aleksandar Tonev arrived, all on loan.

Former Espanyol and Villarreal player Wakaso was set to sign before the first-leg draw against Maribor but work-permit issues held him up until after Celtic crashed out of the play-offs with a 1-0 home defeat on Wednesday night, which sent them into tomorrow’s draw for the Europa League group stage.

That defeat might have an impact on their bid to buy Sporting Gijon forward Stefan Scepovic.

The Serbian has been quoted as saying he has several options other than Celtic, including PSV Eindhoven, but Hoops manager Deila said after the home defeat by Maribor that discussions were ongoing.

Celtic’s transfer policy has come under ever-increasing scrutiny over the summer with criticism exacerbated by their 6-1 aggregate defeat by Legia Warsaw, which was overturned following an administrative error by the Poles, and now the loss to the Slovenians.

Celtic have taken in more than £30million in transfer fees since the end of the 2012-13 season, during which time they beat Barcelona.

But their failure to obtain adequate replacements for the likes of Gary Hooper, Victor Wanyama and Joe Ledley has now seen them miss out on Champions League income of about £15million.

However, despite criticism of a lack of spending this summer, they have shelled out close to £15million on players since May 2013, but with limited success.

Only Virgil van Dijk has looked like fitting Celtic’s recent ideal profile of a young foreign player who develops at the club and is then sold on for a profit.

The Dutch defender arrived for a fee of about £2.6million and has been linked with an £8million switch to the likes of Newcastle and Southampton.

Others who have come in for similar fees have failed to make their mark – Portuguese forward Amido Balde, Finland striker Teemu Pukki, and Dutch winger Derk Boerrigter.

Norwegian midfielder Stefan Johansen has made more of an impact but could not help Celtic overcome Champions League opposition they would expect to beat, while Israeli midfielder Nir Bitton and Australia’s Tom Rogic have failed to add to the team.

While Wanyama and previously Ki Sung-yueng made the club a huge profit there were also earlier abject and expensive failures including the purchases of Mo Bangura and Efrain Juarez.

Celtic’s wage structure has prevented them signing more expensive players.

The only Scot to arrive before Gordon in recent years has been Leigh Griffiths, who has struggled to win over Deila after scoring seven goals last season after joining from Wolves in the final moments of the January transfer window.