The California student who was forgotten about by agents and left alone in a holding cell for five days without food or water filed a $20 million claim Wednesday against federal drug officials.

Attorney Eugene Iredale sent the demand notice on behalf of UC San Diego senior Daniel Chong, 23, to the Drug Enforcement Administration's (DEA) general counsel, the San Diego Union-Tribune reported.

Chong had been picked up in a drug sweep but was never arrested or charged.

"The deprivation of food and water for four and one-half days while the person is handcuffed the entire time constitutes torture under both international and domestic law," the claim said.

Chong has said he was eventually forced to drink his own urine to survive after being detained and locked in the five-by-10-foot windowless cell after a drug raid on April 21.

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He was discovered April 25 and rushed to the hospital, where he spent five days being treated for a perforated lung, possible kidney failure and other illnesses.

Earlier Wednesday, the DEA issued an apology to Chong in the form of a statement from the top federal drug agent in San Diego, acting special agent in charge William R. Sherman.

"I am deeply troubled by the incident that occurred here last week," the statement said, without mentioning Chong by name. "I extend my deepest apologies to the young man and want to express that this event is not indicative of the high standards that I hold my employees to. I have personally ordered an extensive review of our policies and procedures."

The repercussions from the incident reached Washington on Wednesday, with Rep. Darrell Issa (R-Calif.), chairman of the House Committee on Oversight and Government Reform, set to review the case.

"Chairman Issa and the Oversight Committee will be asking the DEA for an explanation of this outrageous incident," Issa's spokesman, Frederick Hill, told the Union-Tribune.

Meanwhile, Sen. Barbara Boxer (D-Calif.) sent a letter to Attorney General Eric Holder requesting an investigation.

At a news conference Tuesday, Chong said he screamed and kicked at the door of his cell but days passed while he was locked inside.

"I heard them around me," he said. "Every door opening around me."

The engineering student said he became badly dehydrated and began hallucinating after two days. He bit his eyeglasses to break the glass and scrawl the words "Sorry Mom" on his arm. He also tried to eat some of the glass amid his confusion.

"I had to recycle my own urine," Chong said. "I had to do what I had to do to survive."