Washington  - Illinois Senator Roland Burris, who filled Barack Obama's vacated Senate seat last month, acknowledged in documents made public Saturday that the state's governor's brother sought donations from him.

Burris, 71, claimed that he didn't respond to the request, which came in the months before his appointment as senator. He said in an affidavit that he refused the request as it "could be viewed as an attempt to curry favour with him (governor) regarding his decision to appoint a successor" to Obama.

Illinois Governor Rod Blagojevich was thrown out of office on January 29 by state legislators on criminal corruption misconduct charges that included a plot to sell President Obama's vacated US Senate seat to the highest bidder.

Federal agents arrested Blagojevich outside his Chicago home on December 9. They said wiretaps of phone conversations showed Blagojevich was exploring ways to profit or personally benefit by using his authority to appoint Obama's successor in the Senate.

Even after his arrest, Blagojevich remained defiant and appointed Burris to the Senate. Burris was not accused of any wrongdoing but the Democrats believed his appointment was not credible given the allegations surrounding Blagojevich. Burris was sworn in on January 15.

Burris' disclosure Saturday was different from earlier statements, including one under oath, about his interactions with the governor and those close to him. Republican and Democratic lawmakers in Illinois have demanded an investigation into whether Burris committed perjury.

According to the affidavit sent by Burris to the leader of the legislative committee that investigated whether to impeach Blagojevich, he said the former governor's brother, Robert, called him thrice in October and November, and sought his help in raising campaign funds for the governor, the New York Times reported.

Blagojevich was elected governor in 2002 and has been the subject of federal investigation for years. Illinois has long been considered among the most corrupt US states. If Blagojevich is convicted and sent to prison, he would become the fourth of the previous eight Illinois governors to serve time behind bars. dpa