A Kuwaiti, Hajjaj bin Fahd al-Ajmi, considered a financier of Al-Nusra Front, a Syrian rebel group linked to Al-Qaeda, was arrested Wednesday on his return from a visit to Qatar, activists said.
They said on Twitter that Ajmi, 26, was arrested at Kuwait airport.
The UN Security Council last Friday placed Ajmi and five other Islamists on an Al-Qaeda sanctions list, imposing a travel ban and assets freeze.
They are accused of providing money, fighters and weapons to extremist groups.
In early August, the United States also imposed sanctions on Ajmi and two other Kuwaitis for allegedly raising money for Al-Nusra Front.
Kuwait responded by pledging its commitment to fighting terrorism and its funding.