Egyptian authorities have arrested 13 members of the Muslim Brotherhood on suspicion of planting bombs around the Suez Canal to disrupt shipping, security sources said on Monday.
The waterway, the fastest shipping route between Europe and Asia, is a vital source of hard currency for Egypt, particularly since the 2011 uprising that toppled veteran autocrat Hosni Mubarak and scared off tourists and foreign investment.
Egypt's government has escalated rhetoric against the Brotherhood, which it regards as a terrorist group, since the assassination of the country's top prosecutor last week.
The security sources said the men formed a 13-member cell that included an employee at the Suez Canal Authority.
Prosecutors had ordered that they be detained for 15 days and said they had planted bombs in areas including sanitation and electricity facilities as well as on beaches, they said.
No one at the prosecutors' office was immediately available to comment.
The army toppled President Mohamed Mursi of the Brotherhood in 2013 following mass protests against his rule.
The Brotherhood says it is committed to peaceful activism designed to reverse what it calls a military coup, after former army chief, Abdel Fattah al-Sisi ousted Mursi, and then went on to become elected president.
Security forces cracked down hard on Mursi's supporters after he was ousted, killing hundreds in the streets at Cairo protest camps and arresting thousands of others in what human rights groups described as a return to repression.
Since then, state-run media has demonised the Brotherhood.
Last week Egyptian security forces stormed an apartment in a western Cairo suburb and killed nine men whom they said were armed, the interior ministry said.
Among the dead was a prominent lawyer for the Brotherhood and a former lawmaker. The Brotherhood denied that the men were armed and said they were holding an "organisational meeting".
Egypt does not distinguish between the Brotherhood and groups such as Islamic State, which has an affiliate in Sinai, epicentre of an Islamist militant insurgency that has killed hundreds of soldiers and police since Mursi's fall.