Indian Prime Minister Narendra Modi has visited the town of Morbi in his home state of Gujarat to see for himself the scene of Sunday's bridge collapse, which left 135 people dead.

The 140-year-old bridge over the Machchu river gave way days after it reopened following repairs.

Divers are continuing to search for the remains of victims.

Nine people, including employees of a firm contracted to maintain the bridge, have been arrested.

The 230m (754ft) bridge was built in the 1870s during British rule.

Described by the state's tourism website as a "technological marvel", it reopened last week after being shut for months for repairs.

Many victims were swept away by the fast-moving water. Officials said that most of victims were women, children and elderly people.

After Mr Modi visited the scene on Tuesday, his office said he stressed the need "to conduct a detailed and extensive inquiry", adding: "the key learnings from the inquiry must be implemented at the earliest."

By Geeta Pandey, Morbi, Gujarat

At the government-run civil hospital which I visited in the morning, I saw men bringing in new mattresses and clean linen for the injured patients.

For the townspeople, life is limping back to normal - shops are reopening and there's traffic on the streets.

But it's all quiet at Jhulto Pul, one of the town's most prominent tourist spots and the scene of Sunday's tragedy.

The only sounds one hears there are the purring engines of rescue boats as they continue to criss-cross the muddy river waters, looking for any more bodies.

On Monday, teams of emergency workers scoured the river in small boats, paddling through its muddy waters and the mangrove shrubs in search of the missing. Hundreds of locals too joined in the efforts, while distressed relatives searched for their loved ones.

By evening, the rescuers had managed to recover 134 bodies. Search operations resumed on Tuesday morning. At least 170 people have been rescued so far.

Gujarat has announced a day of mourning on Wednesday.

Authorities have promised a full investigation after questions were raised about whether safety checks were carried out before the bridge was reopened.

Police say the nine people arrested are all associated with Oreva group, the firm contracted to maintain and operate the bridge.

They include two managers, two ticket clerks, two contractors and three security guards. They are being investigated for culpable homicide not amounting to murder, senior police officer Ashok Kumar Yadav said.

The firm has been accused of multiple lapses, including its alleged failure to get a fitness certificate from the municipality.

Oreva has not responded to questions about the collapse. Some are asking if top-level managers in the company will also be investigated.

The tragedy has devastated the people of Morbi, a little town known for its thriving ceramic industry.

On Monday, the two main crematoriums in the city were full, even as the search for survivors continued. In cases where entire families were wiped out in the accident, locals took it upon themselves to perform their last rites.

Police have told the BBC the search will continue until everyone is accounted for - but some people were still missing on Tuesday.

Siddique, who went to see the bridge with his friend, says he has been looking for him since Sunday night.

"We were standing in the middle of the bridge when it broke. I clung on to a part of the broken bridge and somehow made my way out, but I don't know where my friend is," he says.