On Monday, the cabinet said the Persian Gulf state's ruling emir had accepted Ajmi's resignation. No reason was given for the move and it was not immediately possible to reach Ajmi for comment. Kuwaiti media reported last month that he had offered to resign before, citing his health.
"The cabinet expresses its sincere appreciation for the efforts of the minister and thanks him for his ministerial work and good achievements," KUNA news agency said in an SMS alert.
Last month Nayef al-Ajmi rejected the comments made in March by US Treasury Undersecretary David Cohen as "groundless and baseless", and was backed by the cabinet.
Cohen said Ajmi had "a history of promoting jihad in Syria" and that his image had featured on fundraising posters for the Nusra Front, a Syrian terrorist group linked to al-Qaeda.
Unlike some other Persian Gulf states, US ally Kuwait is against arming militants fighting to topple Syrian President Bashar al-Assad. But it has tolerated fundraising in private houses, mosques and on social media.
Some Kuwaiti officials fear campaigns that give extremist militant groups funds to buy arms will fuel violence in Syria and stir sectarian tension in Kuwait.
Interior Minister Sheikh Mohammad al-Hamad al-Sabah was appointed acting Islamic Affairs Minister and Cabinet Affairs Minister Sheikh Mohammad al-Mubarak al-Sabah will take on the additional role of acting Justice Minister, KUNA said.
Sheikh Mohammad said last year the Syrian crisis was touching a "very raw sectarian nerve" in the Persian Gulf region.
In a sign that Kuwait is reacting to concerns about the fundraising issue, a Kuwaiti official said a campaign backed by local clerics and politicians was illegal.
Munira al-Fadhli, an assistant undersecretary in the Ministry of Social Affairs and Labor, was quoted by Monday's English language daily Kuwait Times as saying: "Our department does not authorize or license individuals to collect donations. Licenses are only given to official charities".
Fadhli said the "Syria Calls" campaign violated the law and legal action would be taken against its organizers.
"Syria Calls" describes itself as a "Union of Kuwaiti campaigns to support Syria" and is backed by well-known local clerics and opposition politicians. An online poster for the group does not make clear exactly what the money is for.
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