Some victims of the infected blood scandal have been told interim compensation payments of £100,000 due to be made before Christmas have been put on hold.
It is thought at least 10 bereaved families have received letters saying applications approved this month cannot now proceed until they submit new paperwork.
More than 30,000 people in the UK were infected with HIV and hepatitis C after being given contaminated blood products in the 1970s and 1980s.
The government said in October families of people who died as a result of the scandal could apply for interim compensation for the first time.