NEW DELHI (AFP) - Indian police on Wednesday cleared a top aide of prime ministerial frontrunner Narendra Modi of involvement in the 2004 shooting of four people, but he still faces allegations over other killings, a report said.

The federal Central Bureau of Investigation told a court in western Gujarat state there was "not sufficient evidence" to charge Amit Shah over the killings of four people including 19-year-old teenager Ishrat Jahan, the Press Trust of India said.

Police at the time had alleged the four, gunned down on a highway on the edge of Gujarat's main city of Ahmedabad, were terrorists plotting to kill Mr Modi - the Hindu nationalist chief minister of the state.

Shah has been serving as the leading strategist for Mr Modi's opposition Bharatiya Janata Party (BJP) in the pivotal state of Uttar Pradesh during India's marathon general election which has entered its final stages. He has insisted he is innocent of involvement in any killings.

Human rights activists have said the four were victims of a so-called "fake encounter" - or a staged gun battle. The father of one of the victims had sought the arraignment of Shah whom he accused of conspiring with police to organise the killings while he was state home minister.

The case was one of several allegations faced by Shah. who has been named in a preliminary police probe as a suspect in the 2005 killings of a Muslim man who was also accused by Gujarat police of plotting to assassinate Mr Modi. His wife was also shot dead by Gujarat police.

Police alleged that terrorists wanted to kill Mr Modi in revenge for the deaths of at least 1,000 people, mainly Muslims, in riots that swept the state in 2002.

Shah also faces an inquiry for alleged illegal snooping in 2013 on a female architect in Gujarat.

He is widely expected to take a senior role in a Modi government if, as polls forecast, the BJP defeats the ruling Congress party in the election. A CBI spokesman confirmed to AFP it had filed a court affidavit but would not disclose its contents.

"There was absolutely no evidence against Amit Shah in this (2004) case," BJP spokesman Nirmala Sitharaman told AFP.

Extra-judicial killings are nothing new in India, with a number of cases having come to light in recent years in restive Indian-administered Kashmir, the country's only Muslim-majority region. There are also many cases in other parts of India.