The donations are against the law because Zeituni Onyango, a half-sister of Obama's father, is a citizen of Kenya, The Times of London reported. Campaign laws require all donors to U.S. political campaigns to be U.S. citizens.

The Obama campaign said Onyango contributed a total of $265 and all the money would be returned, CNN reported.

In his book, "Dreams From My Father," Obama described his meeting with Onyango in Kenya in 1988.

"'Welcome home', Zeituni said, kissing me on both cheeks," Obama said.

But Onyango told the Times she had spent much of her time in the United States.

"I have been coming to America ever since 1975," she said. "I always come and go."

A U.S. wires service reported Friday that a judge four years ago rejected Onyango's asylum application and ordered her to leave the United States. The Obama campaign said the candidate knows nothing of his aunt's immigration status and that all illegal contributions would be returned.

Rep. John Conyers, D-Mich., chairman of the House Judiciary Committee, has asked Homeland Security Secretary Michael Chertoff to determine if information on Obama's aunt was illegally leaked, CNN said.