The US Treasury has levied sanctions on 16 individuals and entities across the Horn of Africa and the Middle East, accusing them of laundering money for the Al-Shabaab Islamist militant group.

The Treasury said the "expansive business network" was part of an international fundraising and money-laundering web for the Al-Qaeda-linked group operating in Somalia and designated a terrorist organisation by Washington.

"Individuals within this network include influential business people in the region," the Treasurey said in a statement on Monday.

The targeted entities include Dubai-based fintech Haleel Commodities LLC with branches and subsidiaries in Kenya, Somalia, Uganda and Cyprus.

UAE-based Qemat Al Najah General Trading, which served "as an important money laundering node in the network", and a Kenyan bus company that supported Al-Shabaab's logistics were also slapped with sanctions.

"Al-Shabaab generates over $100 million per year by extorting local businesses and individuals, as well as through the financial support of affiliated businesspeople," the Treasury said.

The funds were distributed worldwide, including to other Al-Qaeda-linked groups, "to sow discord and undermine good governance", it added.

In November 2022, the US imposed sanctions against arms suppliers for Islamic State-Somalia and Al-Shabaab.

Al-Shabaab has been waging a bloody insurgency against the UN-backed government in Mogadishu for more than 16 years.

Although the militants were driven out of the capital by an African Union force, they retain a strong presence in rural Somalia and regularly carry out attacks against political and civilian targets, including in Mogadishu.

The beleaguered central government launched a major offensive against the Islamists in August 2022, joining forces with local clan militias.

But the offensive has suffered setbacks despite early gains.