BRAMPTON, Ont. - An Ontario judge has ruled that it is too soon for two sisters convicted of drowning their mother in a bathtub to be released to be released from prison.

The older sister, now 21, had sought release to a halfway house while her 20-year-old sibling had applied to live with their father.

In a Brampton, Ont., courtroom today, Justice Bruce Duncan said the sisters will have to serve more time in prison before he will consider their application for a conditional release.

The sisters were 16 and 15 when they got their mother drunk, plied her with Tylenol-3 pills with codeine and drowned her in the tub of their Mississauga, Ont., townhouse.

The sisters were convicted of first-degree murder in 2005 and received the maximum 10-year sentence allowed for youths.

The sisters are serving their sentences at the Grand Valley Institution near Kitchener, Ont.