Guns, 6000 amphetamine tablets and the drug ice have been seized during a string of simultaneous raids in Sydney's inner west and Port Stephens, police say.

Part of Darley Street in Newtown was still closed at midday after police say they found a drug lab operating from within a terrace home.

A large police post has been set up on the road outside as emergency services pull apart the alleged makeshift lab.

Police and hazardous materials crews, using oxygen tanks and masks, also targeted a second home in the street.