His cousin Sabeel Ahmed 26, who worked at Halton Hospital in Runcorn, southeast of Liverpool, has been accused of having information that could have helped police prevent another person committing an act of terrorism or arrest and prosecute them for terrorist offences.
No further detail was provided by the Scotland Yard, in line with Britain's strict contempt of court laws that limit reporting before any trial.
Sabeel's brother, Kafeel Ahmed, 27, who suffered serious burns when he drove a blazing jeep Cherokee into the Glasgow airport, remains in a critical condition in a Scotland hospital. Many say his chances of survival are pretty slim.
The Glasgow attack came a day after two Mercedes-Benz cars were found packed with nails, petrol and gas canisters near a central London nightclub.
27-year-old Iraqi doctor Bilal Abdulla, remanded in custody last Saturday was the first to be charged with conspiracy to cause explosions. He is alleged to have been the passenger in the Jeep Cherokee.
Cousins Sabeel Ahmed and Mohammed Haneef thus bring the total number of people facing charges to three in the case.
Three more suspects are still being questioned at a high-security police station in London, while another person has been released.
According to media reports, the SIM card was found in Sabeel Ahmed's car. Haneef had allegedly given it to him before he moved to Australia last year so his cousin could take advantage of remaining minutes of call-time.
Meanwhile, Jordanian doctor Mohammed Asha, 26, and two trainee doctors aged 24 and 27, whose identities have not yet emerged, remained in custody this weekend.
Scotland Yard said today a magistrate had granted detectives until July 21 to detain and question Asha.
The deadline for the other two runs out tomorrow.
In Britain, police have up to 28 days to detain and question them, subject to regular judicial review.
Asha's wife, Marwa Daana, a 27-year-old laboratory assistant, was released without charge on Thursday.
Easily the most surprising case is that of Haneef's. He has been in custody in Australia since his arrest in Brisbane on July 2 as he attempted to leave the country on a one-way ticket.
The Australian Federal Police (AFP) had on Friday decided not to seek extension of the 27-year-old Gold Coast Hospital registrar's detention leading to hopes that he might be released.
Australian Federal Police Commissioner Mick Keelty said in Canberra that police will oppose bail. If found guilty Haneef faces a maximum of 15 years in jail.
"The allegation is that Haneef provided support to a terrorist group," TV Channels quoted Keelty as saying.
The case against Haneef centres around a mobile SIM card, registered in his name, but used by two of the alleged terror suspects, Kafeel and Sabeel Ahmed, over the past year.
Commonwealth Prosecutor Clive Porritt argued Haneef had been "reckless" in giving the SIM card to the two men - his second cousins - but defence barrister Stephen Keim, SC, says the case against him is "extremely weak".
Besides Haneef e-mailed an associate shortly after the failed British terrorist attacks, saying he would have to leave Australia in a hurry, and did not mention visiting his ailing wife and child, according to evidence obtained by federal police.
Meanwhile Attorney-General Philip Ruddock defended the government's anti-terrorism legislation that kept Haneef in detention for 12 days without charge.
He said the police investigation had begun only when the AFP received information about a possible Australian link to the UK attacks.
"Of course having established that there was an individual of interest, the police then have to examine all of the material," Ruddock said.
"And the law envisages, particularly when you are dealing with matters where people are abroad, where you are working through different time zones, where you are dealing with modern technologies, you do need time to be able to assess all of that material."
A review of the laws by a retired judge found they were "substantially achieving the purpose for which they were intended".
"I think the laws have been balanced and appropriate and, in a large measure, appropriate for the risks we face," he said.
"That doesn't mean there won't be fine-tuning arising from the particular experiences that might flow from current investigations.
The charges against Haneef were not brought lightly, he said, but should he be found not guilty he should be able to resume his normal life.
Federal Opposition Leader Kevin Rudd said he is pleased with the way Australian Federal Police handled the case.
"My message to the Australian people is this: that when it comes to terrorism, terrorists and those who support terrorist organisations, this country must continue to adopt a hardline uncompromising stance -- there are no alternatives," Rudd said.
According to The Age Haneef was charged about 7 am (local time) after questioning that started at 4 am and continued in hour-long blocks.
In India, Haneef's wife Firdous Arshiya said the grounds on which her husband was being held were "totally baseless and unfair."
"The Australian authorities knew he had given his SIM to his cousins from the beginning. Why did they have to wait for 12 days to press those charges? He is innocent and Allah will come to our rescue," she said and appealed to Prime Minister Manmohan Singh and Defence Minister A K Anthony to intervene.