A man arrested in connection with the failed London bombings of 21 July has been released without charge.
Police have arrested a total of 37 people in connection with 21 July
His release brings the number of people released to 21, while a further 16 continue to be held in custody.
The man had been arrested in Stockwell, south west London, the day after the failed bombings.
Three of the main suspects are in custody in the UK, and a fourth is being held by Italian authorities as the UK seeks his extradition.
The most recent arrests, of two men, occurred on 1 August after police raids in Clapham and Stockwell.
All 37 people arrested were held on suspicion of committing, preparing or instigating acts of terrorism, but one was then arrested for alleged immigration offences.
Also released on Tuesday without charge were two men and one woman who had been arrested in Brighton two days previously.
A further four men arrested in the same operation will remain in custody until 5 August, the Metropolitan Police said.
SUSPECTED BOMBERS ARRESTED
1: Yasin Hassan Omar, 24, wanted over bomb attempt on a Tube near Warren Street, arrested in Birmingham
2: Muktar Said Ibrahim, 27, suspected of attempting to bomb a No 26 bus in Shoreditch, arrested in North Kensington, London
3: Ramzi Mohammed, wanted over failed attempt to bomb a Tube near Oval, arrested in North Kensington, London
4. Hussain Osman, 27 (also known as Hamdi Isaac) wanted over the Shepherd's Bush attack, arrested in Rome
Meanwhile Hussain Osman, who is accused of being behind the 21 July attack at Shepherd's Bush, has been charged under Italian anti-terrorism laws.
His Italian lawyer said the 27-year-old was charged with association with the aim of international terrorism and with possessing false documents.
The move allows the authorities to continue holding Mr Osman - also known as Hamdi Isaac - and is separate from Britain's attempt to extradite him.
Two of his brothers have also been arrested and questioned by police in Italy.
UK police have also been allowed extra time to question Yasin Hassan Omar, the man suspected to trying to blow up a train between Oxford Circus and Warren Street.
He can be questioned until Wednesday. He was arrested in Birmingham on 27 July.
Two other suspected bombers, Muktar Said Ibrahim, 27, and Ramzi Mohammed, remain in custody after being arrested during an armed raid in London on Friday.
Suspects can be held for a maximum of 14 days under the anti-terror laws before they must be charged or released.