The two unnamed men, aged 46 and 42, were arrested yesterday and have been bailed to return to a south London police station in late June, pending further enquiries.
Scotland Yard is questioning Michael Adebowale, 22, who was shot at the scene on London terror attack, which resulted in the murder of soldier Drummer Lee Rigby in Woolwich, south-east London.
Michael Adebolajo, 28, who was also shot and injured by police in the incident on May 22, spent a second day in custody at a London police station on Saturday after being discharged from hospital yesterday. He is also being held on suspicion of attempting to murder a police officer in relation to the attack on May 22.
Both Londoners of Nigerian descent, believed to be Islamist extremists, were shot and arrested at the scene of the killing and were being held under police guard at different London hospitals.
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Adebowale had been discharged earlier this week and is due to appear in court again on Monday.
Police investigating the Woolwich attack have also arrested a 42-year-old man in north London and a 46-year-old man in east London on suspicion of involvement in the supply of illegal firearms.
The total number of arrests made in connection with the attack stands at 12.
A far-right British National Party (BNP) march is planned in Westminster later after police asked that it be moved from Woolwich.
Events have also been planned in various towns by the anti-Islam English Defence League, while protest group Unite Against Fascism was due to hold a demonstration in Woolwich.
Faith Matters, an inter-faith organisation aimed at tackling extremism, said it had recorded 212 Islamophobic incidents since last Wednesday, up from between four and six per day.
In a statement, Lee Rigby's family stressed that "Lee would not want people to use his name as an excuse to carry out attacks against others."