The prime minister told placard-waving delegates that to increase pay would invite another black Wednesday.
“He said: “This week sees the 15th anniversary of the most humiliating day in the history of British economic policy. Because we must never return to those days, we must always put stability first.”
He said: “Pay discipline is essential. It will be stability first, now and in the future,” adding that there would be no risk of inflation.
Barber’s comments follow a recent walkout by prison officers and nurses and police officers who are also considering action in protest over poor pay offers.
The threat of local government strikes across England, Northern Ireland and Wales also intensified last month after workers voted overwhelmingly to reject a below-inflation pay offer of 2%.