CELTIC are weighing up a move for controversial Mexican striker Nery Castillo, whose 12-month loan deal with Manchester City has just ended.

Parkhead boss Gordon Strachan wants to add more firepower to his squad after the SPL leaders' strike rate dropped in the last couple of months. With the news Shaun Maloney's hamstring injury has been categorised as class A, the worst possible, he will be ruled out for six weeks.

Jan Vennegoor of Hesselink has been missing since October 4, and Cillian Sheridan has dropped back to the reserves after his spell in the first team. So the need to bring in another forward has increased.

Celtic are looking at loan deals as the best way to achieve this, and the English Premier League is just one of the areas which has been searched for likely January signings.

Castillo has been frozen out this season at Manchester City after Mark Hughes took over from Sven-Goran Eriksson, who brought the Mexican in from Ukraine at the end of last year.

Castillo - who played against Celtic in the Champions League last season - had fallen out with the Shakhtar boss Mircea Lucescu, after an amazing incident during a league game in which he demanded to take a penalty against the instruction of the manager ... then proceeded to miss it.

Despite having paid Olympiacos 20million for the striker in July 2007, Shakhtar immediately declared he would not play for them again.

Eriksson saw the opportunity to bring him to Manchester, even though Shakhtar demanded a substantial loan - half of which Castillo agreed to pay himself.

Initially, the pacey Castillo looked to have found a new lease of life, recovering well a broken shoulder which forced him out for several weeks.

But this season he has hardly figured in Hughes' plans and he was set to move to either Real Betis or Roma as the summer transfer window prepared to close at the end of August.

Both deals fell through as it became complicated dealing with Shakhtar and Manchester City.

When the opportunity to move back to Mexico with Deportivo Guadalajara presented itself last month, again getting the necessary clearance from the Ukraine club - who are demanding they get the majority of their fee back before they will sell the player - saw the transfer collapse.

Castillo is desperate to play regular football again as he retains his place in the Mexican national side, and he has made it clear he would prefer to do this in Britain or on mainland Europe.

Meanwhile, boss Strachan has made it clear Polish keeper Lukasz Zaluska's arrival in the summer will not signal the departure of Artur Boruc.

The manager said: "Artur will be staying with Celtic, and I mean beyond next summer."