JAIPUR, India – Police probing bombings in western India that killed 63 people said on Friday that new evidence pointed increasingly towards Indian Islamists backed by a Bangladeshi militant group as being behind the blasts.

Nine bombs, all strapped to bicycles, ripped through a crowded shopping area in the popular tourist city of Jaipur on Tuesday evening. Another 216 people were wounded.

Investigators said the attack bore hallmarks of the Bangladeshi militant group Harkat-ul-Jihad al Islami (HuJI), suspected to be behind several previous blasts in India.

'The modus operandi of the entire operation, the way the bombs were manufactured and concealed in bags are very similar to the way HuJI operates,' Pankaj Singh, a senior police officer in Rajasthan state where the attacks happened, told Reuters.

'It is very possible that Indian groups helped them,' Singh said in Jaipur.

Rajasthan's Parliamentary Affairs Minister R.S. Rathore said on Friday that 18 people, mainly Bangladeshi migrants, were being questioned by police. He also said the latest toll was 63 dead.

India has suffered a wave of bombings in recent years, with targets ranging from mosques and Hindu temples to trains. But few groups have ever claimed responsibility for the attacks.

Islamist militant groups in Pakistan and Bangladesh intent on fanning hatred between Muslims and Hindus in India, and damaging a fragile peace process between New Delhi and Islamabad, are often blamed for bomb attacks in India.

Bangladeshi officials said India should not jump to conclusions.

'While we don't rule out the existence of HuJI in Bangladesh we can say their activity has been drastically controlled by the security agencies here,' Hasan Mahmood Khandaker, director general of the Rapid Action Battalion, told Reuters.

Indian police said they were now looking for Indian suspects and have released several sketches of people who could have been the bombers and the ones who bought bicycles in Jaipur.

An email to local media, from a group calling itself the Indian Mujahideen, claimed responsibility for the attack. Similar claims were made minutes before a blast in Uttar Pradesh state last year.

The email also included a video of a bicycle with a bag strapped to it and showed the bike's serial number, which the police said matched with one of the bicycles from the blast site.

Indian police said they were taking the email 'very seriously', although some police officers and the chief minister have questioned its authenticity.

'Some portions of the email are definitely true, some appears to be wrong and is an attempt to mislead investigations,' Singh said. 'But they did get the serial number right.'

In the email, the Indian Mujahideen declared open war on India and threatened more attacks on tourists.

'From the tourism point of view, this attack is to warn the entire crusaders of the world, U.S. and Britain in particular, we Muslims are one across the globe and you won't find it easy in India as well,' the email, obtained by Reuters, said.

'Don't send your people to India and if you do so then you people will be welcomed by our suicide attackers,' it said. 'This letter is an open warning to India that stop supporting U.S. in the international arena.'

WORRIED TOURISTS

Many foreign tourists said they were scared and were leaving Jaipur, in spite of the police assuring them of safety.

'We saved a lot of money working and then decided to spend quality time in Jaipur, but it has been a shame that we have been stranded in the hotel most of the time,' said Samuel and Emily, a young couple from Southampton in England. 'We are going back.'

Some foreign tourists said they have not been able to shop or move freely inside Jaipur, also known as the pink city because of the colour of its ancient buildings.

'We are very unhappy, we could not shop,' said one tourist, as he boarded a bus along with a group of Americans.

Armed police patrolled the streets of Jaipur's famous old city.

Some local people who have not been able to trace their relatives since the blast were scouting hospitals.

'We have not been able to find our 15-year-old Dasarath. He did not return home that night,' a sobbing relative said.

In the past few years, bomb blasts in Indian cities have killed hundreds of people. The deadliest was in July 2006, when seven bombs on Mumbai's rail network killed more than 180 people.

(Additional reporting by Ruma Paul and Masud Karim in Dhaka; Editing by Alistair Scrutton; Editing by David Fogarty)