PATNA, Jun 12 (PTI): In a clear snub to its coalition partner, an angry Bihar chief minister Nitish Kumar on Saturday cancelled a dinner for the top brass of the BJP in disapproval of an advertisement featuring him with Gujarat chief minister Narendra Modi and another on Gujarat's aid during the floods two years ago.

There was bad blood between the two sides, which run a coalition government for the last nearly five years, after Kumar attacked those who released an advertisement featuring him with Modi, about whom he was always uncomfortable as a political ally.

The JD(U) leader, who has an eye on Muslim votes, has fashioned himself as a secular leader and in the past had avoided sharing any dias with Modi in Bihar.

The dinner he had planned for the BJP leaders attending the National Executive became a casualty in the midst of a vitiated atmosphere and BJP leaders also expressing their reluctance to attend the dinner.

A BJP leader, who declined to be identified, accused Nitish of "over reacting" by attacking Modi.

"He is overreacting. This is not the way to treat your partner". He said that opinion was building up against attending the dinner. Modi was one of the invitees to the dinner.

Earlier, Kumar lashed out at Modi's government for its advertisement on Friday on its "liberal donation" to Bihar during the 2008 Kosi floods, saying it was "uncivilised" to talk about help given during times of tragedy.

He also took strong exception to the use of his photograph with that of Modi in another advertisement published in local dailies and said he would take legal action against those responsible for it.

"The Gujarat government's claim (on flood relief) is uncivilised and against Indian culture. Nobody claims of bestowing favours on those who face tragedy caused by natural calamities," Kumar, who heads the JD(U)-BJP government in Bihar, told reporters here.

He said he would return the "unutilised money" to the Modi Government. "I do not know the exact amount contributed to the Relief Fund by Gujarat. I will go through the details and immediately return the money received from Modi which was lying unspent in the CM Relief account," he said.

Kumar said he or his office was not consulted on the use of his photograph with that of Modi in the advertisement issued by some private individuals.

"It has caused a great embarrassment to me," Kumar said in reply to a question.

"I have no knowledge about the agency advertising my photograph along with that of Modi as published in newspapers today. Nor was my office consulted...I will explore and take all possible legal action against those responsible for this unethical and illegal act," the chief minister said.

Kumar, however, said that such developments would not impact the alliance between the two parties.

His comments have come at a time when the parties are preparing for the assembly elections in the state due later this year. Kumar has kept Modi at an arm's length apparently to woo Muslim voters.

He had specifically asked the BJP not to use Modi, who had received flak for the 2002 Gujarat riots, in its campaign in the state during the 2009 Lok Sabha elections.

A section of BJP leadership felt the advertisements were brought out by those opposed to the JD(U)-BJP alliance.