Washington: The United States tightened financial pressure on Islamic State on Tuesday, slapping sanctions on more than 30 leaders, supporters and affiliates around the world to squeeze the militant group Washington is having trouble defeating.

The Treasury Department designated 15 people as Islamic State supporters for providing technical, logistic or financial backing, working as political leaders or recruiting foreign fighters. The designations allow the government to freeze their assets and bars US citizens from dealing with them.

The State Department named 10 individuals and five groups affiliated with Islamic State as foreign terrorist fighters, a designation that enables financial sanctions and penalties on them and their supporters.

The people and groups designated by the United States came from the United Kingdom, France and Russia to Pakistan, Afghanistan and Indonesia, ‘highlighting the truly global nature of the threat that these actors pose,’ a senior US official told reporters.

The aim is to prevent Islamic State from using its funds to buy weapons and spare parts, and block it from supporting new affiliates that have been emerging around the world, another senior administration official said.

The official called the sanctions ‘a real ramp-up in our efforts’ to prevent Islamic State militants from using the international financial system to spread its cash and influence by supporting affiliated groups.

The action came just ahead of a Leaders’ Summit on Countering ISIL and Violent Extremism, due to be held on Tuesday on the sidelines of the UN General Assembly meetings in New York. The group brings together leaders from more than 100 countries.

Unlike al Qaeda, which uses the financial system to raise revenues from abroad, Islamic State raises funds internally in the territory it occupies in Syria and Iraq, including some $500 million annually in oil revenue and hundreds of millions raised through extortion and taxation, the senior administration official said.

‘That creates a unique problem for us,’ the official said. ‘How we’re dealing with that problem is by trying to financially isolate ISIL within the territory that it controls so that its financial resources do not turn into financial strength.’

The State Department designations included Islamic State’s Khorasan and Caucuses affiliates, as well as the Mujahidin Indonesian Timur, an Islamic State-linked group operating in Indonesia, and the Jund al-Khilafah, a similar organisation in Algeria.

The State Department also designated the Iraq-based Jaysh Rijal al-Tariq al Naqshabandi as a terrorist group. It launched operations against coalition forces in Iraq in 2006 following the hanging of deposed Iraqi leader Saddam Hussein and has continued since then.

Some people targeted for US sanctions were also on a list of four British citizens added to the United Nations’ al Qaeda sanctions list on Monday.

One of the individuals, British citizen Sally Jones, had traveled to Syria to fight with Islamic State alongside her husband, hacker Junaid Hussein, the State Department said. She and Hussein, who has since been killed, published a hit list encouraging people to attack US military personnel, it said.