Narendra Modi, the chief minister of the Indian state of Gujarat, has met the UK's high commissioner in India, thus ending a 10-year boycott of the controversial politician.
Ties with Modi by the UK government were ended after religious riots in 2002.
In some of India's worst inter-faith clashes since independence in 1947, about 2,000 people died in a wave of anti-Muslim unrest triggered by a train fire in which 60 Hindu pilgrims were alleged to be burned alive.
Modi was accused of not doing anything to stop the violence, but he has always denied any wrongdoing and has never apologised for the riots.
Modi has been tipped as a potential future prime minister, partly because of his record of turning Gujarat into one of India's economic powerhouses under his Bharatiya Janata Party (BJP) government.
The UK has had no official contact with him since the communal riots in Gujarat because of his alleged complicity in the violence against Muslims, which saw hundreds killed by Hindu nationalists.
Earlier this month, Britain’s Minister of State of the Foreign Office Hugo Swire had asked Bevan to visit Gujarat and meet Modi to discuss a “wide range of issues of mutual interests”, the British foreign office said in a statement.
"I welcome UK government's step for active engagement and strengthening relations with Gujarat. God is Great," Modi had tweeted, reacting to the meeting with James Bevan, the UK Commissioner to India.
The decision by the UK to resume contact with Modi is seen as a cruel blow to the causes of justice for the massacre's victims (which included three British citizens).
Initially since 2002, Britain had followed a "working policy" of no contact with Modi's government "because of concerns over what happened in Gujarat".
In 2003 Modi was also refused a visa by the US and EU, which had helped to sustain domestic civil society pressure to bring the massacre's perpetrators to justice.
This in turn encouraged the Indian supreme court to intervene by asking the Gujarat government to reopen criminal cases closed for "lack of evidence".
In August,a special court had sentenced former Gujarat minister and former Modi ally Maya Kodnani to 28 years in prison for her role in the riots.
The Congress party, in power nationally, signalled the case would likely feature in its Gujarat election campaign, saying Kodnani's conviction was proof of the BJP's involvement in the riots.
The BJP said the court ruling was proof that the state's criminal justice system was free from bias.
A 2005 federal government inquiry concluded that the train fire had been an accident probably started by people cooking in one of the carriages and was not the result of an attack.
A commission of inquiry set up in 2008 by the Gujarat state government determined that it was the result of a conspiracy.
A 2008 state inquiry exonerated Modi over the riots.