Mr Cameron is the first foreign leader to travel to Egypt since Hosni Mubarak stepped down as president on February 11.
He met Egypt's Prime Minister Ahmad Shafiq and the leader of its Higher Military Council, Field Marshal Mohamed Hussein Tantawi, urging them to show their people they are committed to reforming the country.
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In an interview with the BBC, Mr Cameron said Egypt shows 'good signs' it is moving towards political reform.
"But I would argue and have been arguing with [Egypt's leaders] today that they need to do more, more quickly in terms of ending the state of emergency, allowing political parties to register, freeing political prisoners," he said.
The British Prime Minister also met with the leaders of Egypt's pro-democracy movement. He said they do not have full confidence that Egypt's political reform process is real.
Mr Cameron visited Tahrir Square, the centre of Egypt's mass protests which forced the resignation of President Mubarak.
"As a friend of Egypt we want this transition to happen, we want to help encourage the government to take those steps [towards reform]," he said.
