A group of surviving relatives of 9/11 attack victims has asked President Biden to reverse plans to withhold $3.5 billion belonging to the Afghan central bank in order to satisfy a 15-year-old legal judgment against the Taliban in U.S. courts.

The amount is half of the $7 billion sitting frozen at the New York Federal Reserve since the Taliban takeover of Afghanistan one year ago.

The 76 family members signed a letter to Mr. Biden stating that to use any part of the $7 billion to pay off legal judgments against plaintiffs in the United States is “legally suspect and morally wrong.”

In February, Mr. Biden issued an executive order that would allow half of the frozen $7 billion to be set aside to be used for humanitarian relief in Afghanistan; the remainder would be used to settle lawsuits filed against the Taliban by another group of surviving relatives of the attack.

The 47 relatives in that lawsuit, collectively known as the Havlish plaintiffs because of the name on the original lawsuit, won a judgment in 2006 against the Taliban but were unable to collect on it. The collapse of the Afghan government, the subsequent takeover by the Taliban, and the freezing of the country’s assets last year opened up the possibility that at least some of the money would make its way to the victorious plaintiffs and their lawyers.

Since then, several other groups representing victims of the 9/11 attacks have come forward demanding a share of the $3.5 billion. The scramble has led to infighting among the various legal teams — some of whom will receive significant windfalls if the cash is ever dispersed — over who is entitled to a share of the money and how much.

The authors of the letter to Mr. Biden, released Tuesday and first reported by Politico, acknowledged that the legal claims made by the various groups of family members are complex, but said that the arguments underpinning them are based on the false notion that the frozen money belongs to the Taliban. The money, they assert, belongs to the Afghan people, who need it much more than the families involved in the American lawsuits.

“Victims of terrorism, including 9/11 victims, are entitled to their day in court,” the letter states. “But they are not entitled to money that lawfully belongs to the Afghan people.

“We all lost loved ones on September 11th and call upon you to return the Afghan Central Bank funds to the Afghan people,” the letter asks of Mr. Biden. “This is their money, not ours.”

Since the Taliban re-took Afghanistan in August 2021, the country has been in an economic freefall from which few see much hope for recovery. The billions of dollars in foreign aid that previously propped up the economy have evaporated, and the United Nations now estimates that as much as 95 percent of the population is not getting enough to eat. Nearly 4 million children are said to be undernourished.

Afghanistan’s former president, Hamid Karzai, has described the Biden administration’s decision to withhold the central bank funds as an “atrocity.” He and others have questioned the right of the United States to seize another country’s funds that were invested — as are many country’s funds — in the United States in good faith and in line with international practices.

“Ninety-five percent of Afghans are impoverished, and nearly nine million are at risk of starvation,” the 9/11 families’ letter to Mr. Biden said. “Affirming that these funds belong to the Afghan people will not solve Afghanistan’s problems; figuring out how to transfer the money directly to the Afghan people is a formidable task. But the point is: this money is theirs, not ours. Simply put, this money belongs to the Afghan people, not 9/11 family members — and they need it more.”