Around 2,000 protesters blocked car ferries from crossing the Suez Canal after a court ruled that 21 soccer fans would be sentenced to death, witnesses told Reuters.
Protesters reportedly also untied moored speedboats used to supply shipping in a bid to disrupt passing vessels.
Military police recovered five boats and brought them back to shore in Port Said, but two were still drifting, one witness said.
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A fine start to the Bank Holiday weekend but some rain will arrive by Sunday.
A rapist has been given three life sentences for a vicious attack on an 81-year-old woman minutes after he sat next to her on a bus.
Ming Jiang, 43, was heavily in debt and chased by creditors when he murdered his wealthy friend.