At least one person has been killed and more than 40 have been left wounded after hundreds of Christian protesters clashed with riot police in Egypt.
The scuffles began after authorities halted the construction of a church in Cairo, claiming workers did not carry a valid permit.
Riot police were seen hurling rocks and firing tear gas into the crowds of protestors.
Sectarian tensions simmer below the surface in Egypt, but the Christian protesters said this wasn't aimed at Muslims - targeted instead at the authorities and their mishandling of those tensions, Sky News Australia reports.
The attorney general decided to hold the 156 protesters for 15 days on suspicion of inciting the riots, MENA reported. It did not say whether they had been formally charged.
Some Christians demonstrated near the church and others near the Giza governor's office. Christians make up 10 percent of Egypt's 79 million people.
The Interior Ministry said on Wednesday that at least 112 protesters had been detained in the Giza area, where the authorities had halted construction of the church although the Copts said they had an official permit, Reuters says.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?
The TurkStream, which runs along the bottom of the Black Sea from Russia's Anapa to Turkey, will consist of two lines, each with a capacity of 15.75 billion cubic meters of gas a year