Renato Corona, the Philippines' chief justice, has been rushed to the hospital after he walked out of his own impeachment trial in the senate, his spokesman has said.
Corona, who has denounced the impeachment proceedings over alleged graft as personal vendetta by President Benigno Aquino, checked into hospital on Tuesday night.
"The diagnosis is a possible heart attack," his spokesman Midas Marquez said in several radio interviews.
Corona, who faces accusations of failing to declare up to $12m in 82 bank accounts under his name, has since been transferred to the hospital's intensive care unit for constant monitoring.
He is also accused of blocking the prosecution of Gloria Macapagal Arroyo, Aquino's predecessor, who was arrested last year on vote-rigging charges and later charged with corruption.
Corona's hospital admission could delay resolution of his impeachment trial, which analysts warn has caused deep political divisions in the Southeast Asian democracy.
Corona and 11 other justices on the 15-member Supreme Court were appointed by Arroyo.
The chief justice has said he would open his bank accounts for inspection if the 188 lawmakers behind his impeachment follow suit.
Corona's senate trial to decide whether or not he should be removed from office began a month after Aquino's Congressional allies impeached him in December, the first such move ever against a chief justice of the Supreme Court.
The proceedings have since gripped the nation with millions watching the drama live on TV.
The judge, who previously had a heart bypass operation, stunned the senate when he abruptly walked out following his testimony on Tuesday.
Corona was later brought back in a wheelchair, after his lawyers said he had fallen unwell.
Senate president Juan Ponce Enrile had ordered Corona to take the stand again on Wednesday for cross-examination, and warned his testimony would be struck off the record if he failed to do so, but doctors say Corona will not stand trial due to the medical issues.
The defence has been given until Friday afternoon to finish presenting its case - with or without Corona
The top judge says his trial was in retribution to last year's landmark Supreme Court verdict that ordered the president's clan to break up a sprawling sugar plantation and hand plots over to farmers.
If convicted, Corona would lose his job and might face additional criminal charges.