Brent crude slipped by 79 cents to $99.91 a barrel as stimulus measures by global banks failed to allay investor fears about oil demands.
Central banks in China, the eurozone and the UK eased policies on Thursday, underscoring growing worries about the global economy, reports Reuters.
A dispute over labour in Norway, however, is expected to check losses. Oil unions in the country moved to lock-out offshore workers on the Norwegian continental shelf on Thursday in an attempt to put an end to a two-week strike.
Meanwhile, US crude also fell 89 cents to $86.33 a barrel as investors wait for a jobs report which is set to provide clues on the state of the world's economy.