The Hammers are keen to bolster their defensive options after New Zealand international Winston Reid suffered a dislocated shoulder.
And with the international break meaning a brief respite from the day-to-day efforts of training and preparing for a match, Allardyce will step up his efforts to add cover which will help maintain West Ham's promotion push.
Shouldering responsibility: Winston Reid suffered a dislocated shoulder
He said: 'My main priority is to find a central defender to loan for the next two or three months.
'Abdoulaye Faye and James Tomkins were outstanding against Hull on Saturday but they were the only two fit defenders we have at the club at the moment.
'I have to fill that position and help us carry on this great run of results that we are on.'
Allardyce has already used the market to his advantage, bringing in Arsenal stopped Manuel Almunia when Rob Green was forced into an extended spell on the sidelines.
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