A representative of Mohamed ElBaradei, the opposition figure, was also in attendance.
ElBaradei, however, told the American television station NBC that he had not been invited to the talks. He criticised the negotiations for being "opaque", saying that "nobody knows who is talking to whom at this stage".
The MB's Fotouh described the meeting as testing the waters for what concessions the government was prepared to make.
He said he "did not see any ... seriousness so far. They [the government] have failed to take concrete measurement on the ground.
"If they were serious, the parliament would have been dissolved, also a presidential decree ending the emergency law".
He said that articles 77, 78 and 88 of the constitution should also have been amended by now.
Fotouh was referring to an article of the constitution covering presidential elections, which now effectively puts Mubarak's governing NDP party in a position to choose the next president, and another that allows the president to run for unlimited presidential terms.
He said the Muslim Brotherhood "does not seek power" and will not be fielding a candidate for president in elections.
He asserted that the organisation was not prepared to step back from its demand for Mubarak's departure, saying that if it did, the move would be a "betrayal of the martyrs who have died in the these protests".
Official statement
According to a statement from Suleiman's office following Sunday's talks, the government offered to form a committee to examine proposed constitutional amendments, pursue allegedly corrupt government officials, "liberalise" media and communications and lift the state of emergency in the country when the security situation was deemed to be appropriate.
On Sunday, the Reuters news agency said that cables leaked by the whistleblower website Wikileaks showed that Suleiman has often told US officials that the Muslim Brotherhood "had spawned '11 different Islamist extremist' organizations".
The revelations throw doubt over Suleiman's ability to act as an honest broker in talks with the opposition, in which the MB is the largest party.
A proposal being promoted by a group of Egyptians calling itself the The Council of Wise Men involves Suleiman assuming presidential powers for an interim period pending elections.
But some opposition figures argue that would mean the next presidential election would be held under the same unfair conditions as in previous years.
They want to first form a new parliament to change the constitution to pave the way for a presidential vote that is democratic.
Issam al-Aryan, a leading Muslim Brotherhood member, said that the organisation would hold a news conference on Sunday evening to announce what was discussed in the meeting with Suleiman.
Both he and Mohammed Mursi, another senior leader, said that the group would be sticking to its demand that Mubarak resign.
An Al Jazeera correspondent in Cairo described the news of the MB joining the talks as "highly significant".
"They are interested in talking about the resignation of president Mubarak," he said. "They want parliament resolved, they want those responsible for violence of the last few days put on trial ... and wanting to be able to peacefully protest."
Al Jazeera's correspondent in Alexandria - one of the Muslim Brotherhood's strongholds - says many people are surprised by the group's decision to enter talks.
He said it is a major concession that might be seen as a "weakness" in the sense that the MB did not stick to its stated position against joining negotiations until Mubarak resigns.
Cherif Bassiouni, president of the Egyptian American Society and a former UN human rights expert, said the MB has already proved itself to be a responsible participant in Egypt's legislative process.
"They participated in the 2005 legislative elections. They elected 88 members to the parliament. So they've had a role in the secular parliament," Bassiouni said.
Essential Vocabulary: opaque: 불투명한/concrete measurement: 확고한 조치
