The Indian Deputy Prime Minister, LK Advani, has suggested the killing of a Hindu nationalist leader may have "terrorist" connections.
Haren Pandya: Shot in the chest and neck, reports say
He was speaking at the funeral of Haren Pandya, a former minister in the state of Gujarat.
Unidentified gunmen killed Mr Pandya, a leading figure in the governing Bharatiya Janata Party (BJP), in the state's commercial centre Ahmedabad on Wednesday.
He was cremated in the presence of senior BJP leaders amid tight security.
Mr Advani told reporters: "A terrorist-cum-underworld nexus seems to have been responsible for the murder of Haren Pandya".
Mr Advani stopped short of naming any group or individual he thought may be responsible for the attack. But BJP president Venkaiah Naidu said he did not rule out a link with an underworld boss, Dawood Ibrahim.
Last year, Gujarat witnessed some of the worst religious riots in decades and the authorities are anxious to keep a lid on tensions.
Earlier Mr Pandya's body was brought to the BJP headquarters in Ahmedabad where Mr Advani, Mr Naidu and Gujarat Chief Minister Narendra Modi laid wreaths.
Exactly what happened during Wednesday's shooting and how many gunmen were involved is still unclear.
Senior BJP leaders attended the funeral
Mr Pandya was returning from his morning walk when he was shot at close range. He died later in hospital.
Some early reports say the shots were fired from a passing vehicle which drew up alongside Mr Pandya and then sped off.
"He was shot in the chest and neck," a police officer told Reuters news agency,
adding that police were checking a motorcycle found abandoned near the car.
Appeal for calm
BJP leaders, led by Prime Minister Atal Behari Vajpayee, were quick to express deep shock at Mr Pandya's death.
December 2002: BJP easily wins state elections
October 2002: 31 Hindus killed in temple attack
February onwards: Godhra attack sparks riots in which more than 1,000 people die, most of them Muslims
February 2002: 58 Hindus burned to death in Godhra train attack
The BJP president in Gujarat, Rajendra Singh Rana, appealed for calm.
"It's unfortunate, but let's not jump to any conclusions and create a situation which will create a law-and-order problem," he told Reuters.
Mr Pandya was a former home minister and revenue minister in the state government and an important member of the BJP in Gujarat.
He was also a senior member of the right wing pro-Hindu organisation, the RSS.
He was reported to have had bitter differences with the state's chief minister, Narendra Modi, who was widely criticised for his handling of last year's unrest.
Mr Pandya refused to contest the Gujarat elections held last year, in which the BJP was re-elected in a landslide victory.
In the Gujarat violence last year a suspected Muslim mob burned 59 Hindus alive in a train.
In wide-scale revenge attacks, more than 1,000 Muslims were killed - independent observers place the number at closer to 2,000.