The Iranian government has closed one of the country's top three newspapers, detaining its editor and cartoonist, for publishing a caricature that caused members of Iran's Azeri minority to riot in protest.

The cartoon, printed last Friday, provoked large disturbances in Tabriz, the capital of eastern Azerbaijan province, yesterday. Police fired tear-gas as rioters smashed windows of the local governor's office.

According to one Azeri website, "some 200 persons were arrested, over 50 severely injured and at least four persons have lost their lives" during the disturbance.

State television reported that the press supervisory body had closed the state-owned Iran newspaper "due to its publication of divisive and provocative materials".

The closure would be indefinite. It is the first time a newspaper has been banned since Mahmoud Ahmadinejad became president last year.

Tehran prosecutor Saeed Mortazavi said the paper's cartoonist and editor-in-chief had been detained.

"Those responsible, the cartoonist and the chief editor, were summoned and the charges were read to them. The two were taken to Evin prison," Mortazavi said. Culture minister Saffar Harrandi apologised for the cartoon yesterday and promised to punish the editor and cartoonist.

Eshrat Shayegh, an Azeri MP, said the apology came "at least one week" too late. Azeris make up about a quarter of Iran's 70 million people.

The cartoon showed a boy repeating the Persian word for cockroach in different ways, while the uncomprehending bug in front of him says "what?" in Azeri.

Mr Neyestani's family said he had not returned from court and insisted that he had not intended to insult Azeris. Azeris speak a language related to Turkish.

Although they have many luminaries among Iran's commercial elite, Iran's majority Persians mock them as stupid.

Iran's conservative judiciary has closed more than 100 mostly pro-reform newspapers since 2000. However, today's closure came from a government agency rather than judges.