The United States has blocked the import of goods suspected to have been made with forced labour from five countries, including clothing from China and diamonds from Zimbabwe, officials said on Tuesday following a rare crackdown on slave labour abroad.

The U.S. Customs and Border Protection (CBP) said it seized five different products this week based on information indicating the goods were made using slave labor overseas.

The other items included rubber gloves made in Malaysia, gold mined in the Democratic Republic of the Congo and bone black – charred animal bones – manufactured in Brazil.

Under a 2016 law, it is illegal to import goods into the United States that are made entirely or in part by forced labor – which includes prison work, bonded labor and child labor.

“A major part of CBP’s mission is facilitating legitimate trade and travel,” said Acting CBP Commissioner Mark Morgan.

“CBP’s issuing of these five withhold release orders shows that if we suspect a product is made using forced labor, we’ll take that product off U.S. shelves,” he said in a statement.

A company hit with a withhold release order can decide to reroute the shipment and try to sell their products elsewhere or persuade CBP to change its decision by providing documents to demonstrate due diligence and argue the goods are slavery-free.

More than $400 billion worth of goods likely to be made by forced labor enter the U.S. market each year, according to estimates by the Human Trafficking Institute, a non-profit.

Yet reporting by the Thomson Reuters Foundation in April found that only $6.3 million worth of goods had been blocked since the law banning slave-made imports was passed in 2016.

Prior to the latest crackdown, the CBP had issued seven detention orders since 2016, including chemical compounds, peeled garlic and toys from China and cotton from Turkmenistan.

“It’s exciting to see CBP’s progress toward robust enforcement of this law,” said Annick Febrey, head of government and corporate relations at the Human Trafficking Institute, who in April described the agency’s impact until then as “minimal”.

“This is a clear signal to companies that they need due diligence procedures in place that prevent forced labor in their supply chain if they want to sell in the United States.”

Neha Misra, senior specialist in migration and human trafficking for advocacy group Solidarity Center, welcomed the “significant step” and said economic pressure could boost the drive for full labor rights for workers in global supply chains.

The U.S. Department of Labor said last year it was boosting its fight against slave-made goods “to safeguard American jobs” for its 325 million citizens and that it was playing a key role in protecting vulnerable workers from abuse worldwide.

About 25 million people globally are victims of forced labor, according to the U.N. International Labor Organization.