Thousands of conservative Muslims protested in the Indonesian capital on Friday after a flag linked to a banned Islamic group was burned by members of the country's largest mainstream religious organisation.

Waving black flags bearing the Islamic declaration of faith, several thousand demonstrators, many wearing white Islamic robes, filled a major thoroughfare in Jakarta after Friday prayers.

Video of members of Nahdlatul Ulama's youth-wing militia burning the Hizbut Tahrir flag last month has sparked allegations of blasphemy because it was emblazoned with the Islamic declaration of faith.

Hizbut Tahrir, which seeks a global caliphate, has been banned by the Indonesian government as a threat to national unity.

Religious and ethnic tensions are likely to rise in Indonesia as April's presidential election nears. Indonesian President Joko Widodo has chosen a conservative cleric as his running mate to head off criticism he's insufficiently Islamic.

A protest was also staged on Friday in Garut, West Java province, where the flag was torched after hard-liners allegedly infiltrated an event organised by Nahdlatul Ulama's youth wing.

Indonesia's moderate reputation was undermined last year when Jakarta's minority Christian governor was imprisoned for blasphemy following street protests against him that drew hundreds of thousands.

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