WASHINGTON, Aug 18 (Reuters) - President Joe Biden"s Justice Department is stepping up its fight against a new state law in Missouri that aims to invalidate many federal gun regulations, saying the measure has impeded law enforcement efforts to work with state and local police and is also unconstitutional. On Wednesday, the Justice Department filed a statement of interest in an ongoing lawsuit in Cole County, Missouri, saying the state"s Second Amendment Preservation Act, also known as "HB85," should be declared unconstitutional and that the court should issue a injunction barring its enforcement. "HB85 is legally invalid. Under the United States Constitution’s Supremacy Clause, the State of Missouri has no power to nullify federal laws," the department"s filing says. In an accompanying sworn statement, Alcohol, Tobacco, Firearms and Explosives Special Agent in Charge Frederic Winston said the new law "has already had a significant impact on ATF"s partnerships with state and local law enforcement offices," noting that 12 of 53 state and local officers have withdrawn from participation in ATF task forces since the law"s enactment. A hearing in the case, which was filed by the City of St. Louis et al against the State of Missouri et al, is slated for Thursday. The Justice Department"s court filing marks the latest move by Attorney General Merrick Garland to quash executive orders or laws in red states that clash with the enforcement of federal laws. Earlier this month, the Justice Department secured a legal victory in Texas, after a federal judge temporarily halted an executive order by Governor Greg Abbott that restricts the transport of migrants through the state and authorizes state troopers to pull over vehicles suspected of doing so. HB85, which was signed into law in June, purports to nullify various federal firearms laws. The Missouri law comes at a time when the Justice Department has sought to crack down on illegal firearms, launching a firearms trafficking task force thissummer to trace the origins of guns used to commit crimes. Reporting by Sarah N. Lynch in Washington Editing by Matthew Lewis Our Standards: The Thomson Reuters Trust Principles.