Egypt deployed security forces outside metro stations on Sunday, witnesses said, a day after more than 20 people were detained following protests by commuters angry at fare hikes.
Public discontent has been on the rise in Egypt as the government presses on with economic reforms, including curbs on state subsidies, agreed in a 2016 loan deal with the International Monetary Fund.
Security sources said at least 22 people were detained by police in "limited and sporadic protests" on Saturday at several metro stations by commuters demanding that price hikes be reversed.
They said most had been released, with three detained for 24 hours pending further investigation.
A judicial source said the public prosecution in Helwan ordered seven men and three women be detained for four days for questioning on suspicion of illegal congregation at the metro station in the southern Cairo suburb, disturbing public order and obstructing a public facility.
The 10 could face up to five years in jail if charged and convicted said their lawyer, Fatma Serag, of the Association for Freedom of Thought and Expression (AFTE).
Protests have become rare in Egypt since a law passed in 2013 banned demonstrations not approved by the Interior Ministry, taking away a right earned in the 2011 uprising that toppled long-time autocrat president Hosni Mubarak.
The government says higher fares are needed to keep the loss-making metro running and to finance new extensions to serve more of the capital's 25 million people. More than three million use the metro every day.
The price rises, which came into effect on Friday, tripled the cost of some metro tickets.
"The increase will generate about one billion pounds [Dh0.2bn]," Transportation Minister Hesham Arafat told television channel Sada Al Balad on Saturday, saying that without the extra funds "the metro company cannot continue".
State news agency MENA said the metro system had accumulated losses of 617 million pounds (Dh127m).
The government previously angered Cairo residents when it doubled the price of many metro tickets last year.
There were no signs of fresh protests on Sunday, the first day of the working week, but commuter numbers in the morning rush hour seemed lower than usual, witnesses said, adding that security force vehicles and extra officers were outside several stations.
Videos posted on social media on Saturday had shown people jumping over ticket barriers at some stations, while at others, dozens of protesters chanted slogans as police looked on. The authenticity of the recordings could not be confirmed.
One witness saw police detain at least two people after scuffles.
Interior Ministry officials could not be reached for comment.