Anti-gay marriage move by Tas Libs

A move against the legalisation of gay marriage by Tasmania's ruling Liberal party has been labeled archaic.

At the party's annual state conference in Launceston on Saturday a motion was carried in support of the current Commonwealth Marriage Act, which outlines a union between a man and a woman.

Australian Greens leader and Tasmanian senator Christine Milne said the move shows discrimination is alive and well in the state's Liberal party.

"They want to take us back to discrimination ... and as far away as possible from equal opportunity," Senator Milne said on Sunday.

The motion was carried by a clear majority of party members attending the council in Launceston, where Prime Minister Tony Abbott had visited and made an address earlier in the day.

Those in favour of the motion said the Liberal Party should, at a federal level, uphold its belief that marriage is a union between a man and woman to the exclusion of all others.