Families could be forced to turn to emergency foodbanks as they wait for new benefit claims to be processed, a Wiltshire-based charity has warned.
The Trussell Trust is expecting "to feed many more people" as reassessments for incapacity benefit begin.
Emergency food was given to over 40,000 people last year via the 71 foodbanks run by the charity throughout the UK.
Trust director Chris Mould said reassessments can lead to "long delays in payments that see people go hungry".
According to the charity, 15,000 people received emergency food from UK foodbanks in 2009 because of benefit delays and reassessments.
They expect a further increase in demand if an estimated 500,000 people are moved from incapacity benefit to Job Seekers Allowance.
In Wiltshire last year, claimants with benefits issues made up 32%-57% of the 6,734 cases recorded at the foodbanks in Salisbury, Swindon, Devises and Warminster.
"Our biggest fear is the time it takes for benefits to be reassessed," said Mark Ward, Salisbury foodbank manager.
"Not all claimants will lose out when the incapacity benefits are reviewed but any changes made tend to cause a delay to occur so we have to step in to fill the gap."
He said it was too early to tell the level of need but if reviews meant a definite delay, "we could be inundated with people stuck in limbo for a few weeks".
The Trussell Trust is a Christian charity which works to alleviate poverty in the UK and overseas.
Members of the public donate food which is then distributed to people through a voucher system.
"I personally don't fear that we will run out of food immediately because the people who support Salisbury foodbank (a large section of the community) always come up trumps," added Mr Ward.
"If it is sustained then we may get some 'giving fatigue' or everyone may be feeling the pinch which will force them to cut back their giving."
The director of the charity is urging the Department of Work and Pensions to talk to The Trussell Trust foodbank network - and other charities like CAB and Salvation Army - about how they can help ensure that people being reassessed do not find themselves forced into damaging situations.