By Gabriele Pileri
ROME (Reuters) - Italy's parliament began debating a proposal on Thursday to give gay civil partnerships legal status, a bill that faces fierce resistance from the Roman Catholic Church and opposition parties in the only major Western country not to recognize such unions.
The bill, which also relates to heterosexual partnerships, would give unmarried couples rights including being allowed to adopt each others' children in some circumstances and to inherit their partners' pensions.
Last week, Pope Francis appeared to weigh into the debate, defending traditional marriage as "the family God wants".
The debate in the Senate, or upper house, was mainly on technical aspects such as whether the law respected the constitution but supporters hailed it as a step forward after several attempts to introduce such legislation since the 1980s.
"For the first time after so many attempts ... a draft law that aims to legislate on gay people's rights is finally being discussed," gay rights group Arcigay's national secretary, Gabriele Piazzoni, said.
The rights being considered are far more limited than those given to married heterosexual couples and the bill could be watered down further as debate continues. The Senate is due to vote on it next week and it then moves to the lower house.
Prime Minister Matteo Renzi promised such legislation soon after coming to office in 2014, but missed self-imposed deadlines due to staunch opposition from his conservative coalition partners.
The European Court of Human Rights condemned the delay last July, but the typically glacial pace of Italian parliamentary process was slowed down even further by thousands of proposed amendments.
Most of the attention has been focused on a plan to allow gay people to adopt their civil partners' biological children, under certain circumstances.
Opponents fear this would lead to full adoption rights and encourage surrogate motherhood, which is illegal in Italy, or in-vitro fertilization, which is strictly regulated.
"Any idiot can see this is a Trojan horse," right-wing politician Giorgia Meloni told reporters on Thursday.
"It will let people go abroad, if they are a couple of women they can get medically assisted fertilization ... if they are men they can do that barbaric thing of renting someone's womb."
Senator Monica Cirinna, the bill's author, told reporters last week that if the "stepchild adoption" provision is amended out of the law "we will have died in battle".
Tens or even hundreds of thousands of opponents of the legislation are expected to rally in Rome on Saturday at a so-called "Family Day". Last weekend thousands marched in almost a hundred cities in support of the bill.
(Writing by Isla Binnie; Editing by Louise Ireland)