The US supreme court has blocked a request by the Trump administration to restart federal executions next week after a 16-year hiatus.

The justices left in place a preliminary injunction by a federal judge, placing a stay on the execution of four men that the US attorney general, William Barr, had scheduled for this month and next month. The first of those had been scheduled for Monday, with a second set for Friday.

The Trump administration, which has embraced the death penalty even as many states have given up the practice, announced in July that it intended federal executions to resume.

The brief order said that the appeals court now considering the case should rule “with appropriate dispatch”.

The conservative justice Samuel Alito wrote a separate statement, joined by his fellow conservatives Neil Gorsuch and Brett Kavanaugh, saying the appeals court should be able to rule within 60 days.

“The government has shown that it is very likely to prevail when this question is ultimately decided,” Alito wrote.

The administration turned to the supreme court after the appeals court on 2 December refused to immediately allow the executions to resume.

A lawyer for death row inmates praised the decision.

“The courts have made clear that the government cannot rush executions in order to evade judicial review of the legality and constitutionality of its new execution procedure,” said Shawn Nolan.

The Department of Justice spokeswoman Kerri Kupec said that while it was disappointed with the ruling, “we will argue the case on its merits in the DC circuit and, if necessary, the supreme court”.

A fifth execution was separately blocked by another federal appeals court.

Most executions in the United States have been carried out by states rather than the federal government, which has gone 16 years without carrying out the death penalty. Protracted litigation over the drugs used in lethal injection executions prevented the government from continuing the practice.

In July, Barr announced that the federal government would resume capital punishment. But last month, a federal judge in Washington blocked the executions, saying that the government’s method of using a single drug to put inmates to death violated the Federal Death Penalty Act of 1994, which requires that executions are conducted “in the manner prescribed by the law of the state in which the sentence is imposed”.

Barr intended for the federal government to replace a three-chemical cocktail, which has been blamed for botched executions, with a single chemical called pentobarbital. Even if the federal government were to use the same drug or drugs required by each state, there were other inconsistencies to consider, including the manner in which lethal injections are administered.

Reuters and the Associated Press contributed reporting