A Metropolitan Police spokesman said the arrests were made over alleged public order offences.
Six males were arrested during the game at Millwall in relation to a banner being unfurled at the game. They remain in custody at this time."
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Motorists who cause death by speeding, street racing or while on a mobile phone are among those who could be handed tougher punishments.
Cubans have lined the streets since Thursday as the ashes of the Communist leader were driven on a 600-mile journey across the island.
It is alleged Mourinho was helped by his advisers to avoid paying tax on earnings from the use of his image rights for product endorsement.