Members of the union Unite, including porters, caterers and cleaners, rejected the 8% deal in ballot by six to one.
The union has already rejected a similar deal on offer for its nurse members.
Unite national officer Peter Allenson said staff were ‘angry and frustrated’ that the government was attempting to tie them into a deal without adequate protection against an uncertain economic climate.
‘The re-negotiation clause, which should come into effect in situations of rising inflation, is not strong enough. We are demanding that the government does more to build-in some security, to protect our members’ pay from deteriorating in the event that the economy takes a turn for the worse,’ he said.
The largest public sector union, Unison, is due to start a ballot of its nurse members this week.