Indian Prime Minister Manmohan Singh has visited survivors of Tuesday's bombings in Mumbai.
Manmohan Singh will visit some of the injured in Mumbai's hospitals
It was his first visit to the city after the blasts, which police say killed nearly 180 people.
His visit comes after Pakistani President Pervez Musharraf offered to help India find those responsible.
Suspicions that Pakistan-based militants may have been involved have raised tensions between the two states.
Manmohan Singh flew into the city amid tight security and immediately drove to the Sion hospital where he met some of the blast victims.
"The prime minister was saying to the patients 'what you want, I will give you,'" Agnes George, who was visiting one of the injured, told AFP.
Mr Singh is also meeting top officials to review security and the investigation into the attack.
Indian security officials have suggested that the Mumbai bombings bore the hallmarks of Lashkar-e-Toiba, a Kashmiri militant group operating from Pakistan.
But the group has not been directly accused and has denied responsibility.
Investigators were widening their hunt for the bombers, probing phone call records in an effort to uncover evidence of a plot, reports said.
Police hope phone call logs could help pinpoint whether a group based outside of India was involved in the bombings.
Sketches of three men wanted over the bombings have been published in the Indian media, but officials admitted they were making slow progress with investigations.
"I cannot say if this is really the first breakthrough. But we hope to have one very shortly," DK Sankaran, chief secretary of Maharashtra state, told the AFP news agency.
On Thursday, the Home Minister of the state of Andhra Pradesh, K Jana Reddy, told reporters that a man on a train in Hyderabad - identified as Abdullah - had been arrested in connection with the bombings.
Vow to help
Gen Musharraf, who was one of the first world leaders to condemn Tuesday's bombings, condemned the loss of "precious lives" in the attacks, in which seven commuter trains were bombed in less than 15 minutes.
But in the days since, there have been sharp exchanges between government ministers in India and Pakistan.
In an interview with a Pakistani TV station on Thursday night, Gen Musharraf said: "Whosoever has done this cannot be pardoned at all...
"I assure Prime Minister Manmohan Singh that the Pakistan government and I myself are with him in any investigation he wants to carry out," he said.
A Muslim organisation banned in India, the Students' Islamic Movement (Simi), is the latest group to deny involvement in the attacks.
At a news conference in the capital Delhi, a Simi leader, Shahid Badr Falahi, described the attacks as deplorable and said his organisation had had no part in them.
Activists of Simi were allegedly involved in bomb blasts in Mumbai in 2003, when 55 people were killed. They are currently being tried in a special court in the city.
Actors join march
On Thursday evening, Bollywood stars such as Anil Kapoor and Hema Malini joined hundreds of Mumbai's residents in a symbolic march to a shrine of the father of non-violent protest, Mahatma Gandhi, reports the BBC's Madeleine Morris.
"Unless justice is ensured, unless the guilty are punished, the situation will get worse," said march organiser Ms Azmi.
Others urged the people of Mumbai not to respond with attacks against the city's Muslim community, and many said they wanted to show that Mumbai would not be cowed by violence.