US attorney general Merrick Garland announced on Monday that the federal government will take action to protect those in Texas trying to obtain an abortion in the wake of the strictest anti-abortion law in the US taking effect last week.

The US justice department said that it will not tolerate violence against anyone seeking abortion services in the state and that federal officials are exploring all options to challenge the ban on almost all terminations, with new state law also empowering the public to enforce the law in a way critics decry as promoting vigilantism.

Garland issued a statement that said the DoJ would “protect those seeking to obtain or provide reproductive health services” under a federal law known as the Freedom of Access to Clinic Entrances (or Face) Act.

Garland said that federal prosecutors are still urgently examining ways to challenge the Texas law and that the DoJ would enforce the federal law “in order to protect the constitutional rights of women and other persons, including access to an abortion”.

The most radical abortion law in the US went into effect on 1 September after the US supreme court did not step in by the 31 August deadline to block it, after an emergency appeal to the highest court, despite concerted legal campaigns.

The near-total abortion ban in Texas empowers any private citizen to sue an abortion provider or anyone deemed to have helped a women get an abortion against the law, although not the patient themselves.

Critics said it was opening the floodgates to harassing and frivolous lawsuits from anti-abortion vigilantes that could eventually shutter most of the dwindling number of clinics in the state. The Texas law also leaves the landmark supreme court case Roe v Wade that led the way to abortion being legal across the US in 1973, hanging by a thread.

The federal law commonly known as the Face Act, meanwhile, prohibits physically obstructing or using the threat of force to intimidate or interfere with a person seeking reproductive health services.

The law also prohibits damaging property at abortion clinics and other reproductive health centers.

The new Texas law prohibits abortions once medical professionals can detect cardiac activity, usually around six weeks – before some women know they’re pregnant.

Courts have blocked other states from imposing similar restrictions, but Texas’s law differs significantly because it leaves enforcement up to private citizens through lawsuits instead of criminal prosecutors, partly as a way to avoid legal review.

Justice department officials have also been in contact with prosecutors, including US attorneys in Texas and the FBI field offices in the state, to discuss enforcing the federal provisions.

“The department will provide support from federal law enforcement when an abortion clinic or reproductive health center is under attack,” Garland said.

“We will not tolerate violence against those seeking to obtain or provide reproductive health services, physical obstruction or property damage in violation of the Face Act.”

After failing to step in before the law came into effect, the supreme court’s five-strong conservative majority then issued a decision in the emergency case, refusing to block the law, with the three liberal justices publishing blistering dissents and being joined by chief justice John Roberts.

Joe Biden called the law unconstitutional and promised efforts by his administration to counter its effects as quickly as possible.

But there is a limit to what the federal government can do.

Ironically, Merrick Garland would have been a supreme court justice if Barack Obama had been able to get his nomination through when he was president. But then Senate majority leader and Kentucky Republican Mitch McConnell blocked the process and the vacancy he had been picked to fill, after Antonin Scalia’s death, went to a Donald Trump pick after the latter won the White House.

After Biden won the 2020 election, beating Trump, he nominated Garland to become his attorney general.