A British charity has warned that enforcing welfare system's reforms will put thousands of families across the country under "unfair pressure".

The charity, Gingerbread, urged the coalition government to postpone plan to cut the benefits paid to unemployed single parents, whose youngest child is five or six-years-old, British media reported.

The group, which campaigns on behalf of single parents, said that at a time of rising unemployment, the move could "cast adrift" 100,000 people.

"The proposed timing of this change is disastrous and will plunge thousands of single parents into a stagnant job market with little prospect of finding work that fits around their caring responsibilities”, said Chief executive Fiona Weir.

"In previous years, single parents have been given plenty of notice of these changes and time to prepare, but the government is rushing this legislation through and will catch single parents unawares”, Fiona Weir added.

"It makes much more sense to delay the change until 2013 when newly-announced childcare support will be available for part-time jobs, which will help single parents of young children balance work and parenting", the charity's boss said.

Gingerbread said single parents will start receiving letters from Friday telling them of changes in the conditions for receiving income support.