Senior ministers are divided over amendments to a bill to decriminalise abortion in NSW, with the Premier voting against one proposed by her Attorney General.

Gladys Berejiklian was among 41 MPs who opposed an amendment by Attorney General Mark Speakman to require terminations be performed "only if the person has given informed consent", which must be given "freely and voluntarily".

NSW Premier Gladys Berejiklian voted against an amendment proposed by her Attorney General. Credit:AAP

The amendment passed 49 votes to 41, as a lengthy debate over a bill to decriminalise abortion continued in the NSW Legislative Assembly.

Health Minister Brad Hazzard also opposed the amendment, arguing it was "unnecessary" as doctors were already required to adhere to the principle of informed consent.