HONG KONG — Police in Hong Kong have raided a homemade-explosives manufacturing lab ahead of another weekend of protests in the semi-autonomous Chinese territory.

Hong Kong media reported Saturday that police also found banners against the extradition bill that has sparked more than a month of demonstrations, but police said they had not established a link to a major protest march planned for Sunday.

Police said they found about 2 kilograms (4.4 pounds) of TATP, a homemade explosive they described as very unstable and extremely powerful. One kilogram was detonated Saturday morning.

Public broadcaster RTHK said a 27-year-old man was arrested. Police said more arrests may follow.

Police have erected huge barricades near government headquarters in preparation for Sunday’s march. A counter-rally in support of the police was being held Saturday evening.