Police said another Indian citizen who was arrested in February in northern India carrying hand-drawn sketches of hotels, the train terminal and other sites that were later attacked was being brought to Mumbai for renewed questioning.
One of the arrested men, Tauseef Rahman, allegedly bought SIM cards by providing fake documents, including identification cards of dead people, senior police official Rajeev Kumar said Saturday in the eastern city of Calcutta.
Rahman, of West Bengal state, later sold them to Mukhtar Ahmed, Kumar said. Both men were arrested Friday and charged with fraud and criminal conspiracy.
The SIM cards were later used by the gunmen.
Police said they were still investigating how the 10 gunmen obtained the SIM cards, and declined to offer more details.
Most large Indian cities, including Calcutta, where the SIM cards were purchased, have thriving black markets for mobile phone cards and cheap phones.
Ahmed was from the Indian portion of Kashmir, the disputed Himalayan region at the root of much of the tension between India and Pakistan, Kumar said.
Indian authorities believe the banned Pakistani-based militant group Lashkar-e-Taiba, which has links to Kashmir, trained the gunmen and plotted the attacks.
Ahmed was believed to be a local police officer, according to a police official in Srinagar, Kashmir's biggest city. The official declined to be named because the matter was still under investigation.
Also Saturday, Mumbai police said they were transporting Faheem Ansari, the man arrested in February, from custody in northern India to Mumbai to answer more questions, hoping he could shed more light on the attacks.
Rakesh Maria, a senior Mumbai police officer, said he believed there was a definite connection between Ansari and the Mumbai attacks.
"Ansari was trained by Lashkar and sent to do reconnoissance," Maria said.
The interrogation of the lone surviving gunman from the Mumbai attacks, Mohammed Ajmal Kasab, 21, revealed that the gunmen had detailed pictures of the locations, Maria said.
"They were pretty elaborate photographs," he said, adding that they had also used maps from Google to study the targets.
News of the February arrest has added to a torrent of criticism about missed warnings and botched intelligence.
Home Minister Palaniappan Chidambaram, India's top law enforcement official, apologized for "lapses" that allowed the gunmen to rampage through Mumbai.
"There have been lapses. I would be less than truthful if I said there had been no lapses," Chidambaram told reporters Friday.
The minister, who assumed his post just days ago following the ouster of the previous minister in the attack's aftermath, spoke as Prime Minister Manmohan Singh pressed the assertion that Pakistani extremists were behind the attack.