After deriding Hillary Clinton for her Indian connections, prompting angry reactions from Indian-Americans, the campaign of Barak Obama, her Democratic party rival in the US Presidential race, has launched a major damage control exercise by expressing 'regret' and offering explanations.

The move is seen as an attempt to assuage the feelings of the influential community, which is becoming a major contributor to election campaigns.

A paper circulated by Obama's campaign among the friendly political correspondents denigrating Clinton's Indian connection with the understanding that they will not reveal the source, became a major embarrassment and a public relations disaster at a time when strenuous efforts are being made to set up 'Indians for Obama' chapters -- on the lines of 'Indians for Hillary' chapters-- across the country.

Confronted by the paper, the Obama campaign expressed regret and asserted that he has been a 'long-time friend' of the Indian-American community.

"Our campaign is fortunate to have strong support of the Indian-Americans across the country," campaign manager David Plouffe said.

"The intent of the document was to discuss the issue of outsourcing but we regret the tone that part of the document took," he said.

But community leaders in New York and elsewhere were still discussing the intent of the Obama's campaign especially its apparent attempt to malign major contributors to and organisers of Hillary Clinton's major fund-raisers, including leading hotelier Sant Chatwal.

The paper circulated by Obama campaign had, in effect, claimed that Hillary Clinton is supporting outsourcing as she is getting hundreds of thousands dollars for her campaign from Indian-Americans and because of that, she does not care about lost American jobs.

Obama had promised to run a clean campaign but apparently his campaign decided to produce what is called the research paper as Clinton consistently scored ahead of him and some recent polls had suggested that she is increasing the lead.

Political campaigns often prepare such papers for friendly reporters who mention the facts without attributing them to the campaign.

But in this case, the Clinton campaign somehow got the paper and handed it over to The New York Times, which confirmed its authorship leading to strong denunciation from Indian-American leaders across the board and demands that Obama himself explain it.

"In this business, half the time we are attacked for not being tough enough and now we are being attacked for being too harsh," campaign's chief strategist David Axelrold told the Times. "The truth is that this is a tough competitive business."

"Will we be judged by a different standard? We have, in many ways, held ourselves to a different standard. (But) when they throw stink bomb at you, you can't be caught unawares," he said.

This is second time that the Obama campaign has suffered embarrassment.

Earlier, it had to distance itself from entertainment executive David Geffen after he said that Hillary Clinton was unelectable and her husband Bill Clinton, former President, untrustworthy. Obama had then asked his campaign 'to be careful not to slip into playing the game as it customarily is played'.