Tonga's public servants association, the PSA, says the government must withdraw its version of political reform and to implement the options suggested by the late Prince Tu'ipelehake.
The union says the prime minister, Dr Feleti Sevele, and the Privy Council sparked last year's riots by suggesting an alternative to the Prince Tu'ipelehake plan.
It also says the changes should be implemented quickly so the constitution can be amended in time for next year's elections.
The PSA also wants the government to roll over wage rises of 60, 70 an d 80 percent that were given following a lengthy strike two years, but which expire in June.
The union says a survey of its members overwhelmingly backed the wage demand and it is giving the government to June 15th to meet it.