He insisted it was too early to draw conclusions about what caused the leak, but said he was "deeply sorry" and that BP would "not rest" until the oil had been cleaned up.
"The explosion and fire aboard the Deepwater Horizon and the resulting oil spill in the Gulf of Mexico never should have happened, and I am deeply sorry that it did," Hayward said, vowing to learn the lessons of such a "terrible event".
But several members of the congressional panel grew visibly annoyed by Hayward's answers to their questions, saying they were less interested in hearing his apologies than in getting answers to what went wrong and why.
Henry Waxman, a Democratic representative, told Hayward that BP had shown "astonishing complacency" regarding safety warnings over the drilling platform which exploded on April 20 killing 11 workers and unleashing the worst oil spill in US history.
Since then millions of litres of crude from the ruptured well have gushed into the ocean every day, with thick black oil choking large swaths of vulnerable coastline, threatening multi-billion dollar fishing and tourism industries and killing birds and marine life.
"Under your leadership BP has taken the most extreme risks," Waxman said.
"BP cut corner after corner to save a million dollars here and a few hours or days there."
Hayward repeatedly declined to go into detail pending the results of investigations into the spill, leading Waxman to snap back: "You are not taking responsibility. You are kicking the can down the road."
The committee members said BP had ignored warnings from contractors and their own employees and chose faster and cheaper drilling options that increased the danger of the well rupturing.
They became increasingly irritated as Hayward side stepped a series of questions on whether he bore any personal responsibility for a series of controversial decisions by saying he was not involved in day-to-day operations.
"I wasn't involved in any decision making," on issues like how to drill, test, or secure the well, said Hayward, who drew a charge from Waxman that he was "stonewalling" the committee.
Hayward, flanked by aides and surrounded by a small army of US Capitol police, walked into the room of the House Energy and Commerce Subcommittee on Oversight and Investigations minutes before his 10:00am (1400 GMT) questioning began on Thursday.
But his opening statement, in which he said he was "deeply sorry" for the spill, was interrupted by a female protester with her hands painted black.
"You need to be charged with a crime, Tony. You need to go to jail," the protester, later identified as Diane Wilson, shouted before being hustled out of the chamber by police.
A day earlier following talks with Barack Obama, the US president, Hayward had agreed to set up a $20bn fund for spill-related damage claims, suspend BP's dividend for the rest of the year and sell off assets to cover the company's costs.
In his testimony on Thursday, Hayward said: "We said all along that we would pay these costs.
|Protester Diane Wilson interrupted Hayward's opening statement [GALLO/GETTY}
"And now the American people can be confident that our word is good."
"We're a strong company and no resources will be spared. We and the entire industry will learn from this terrible event and emerge stronger, smarter and safer."
Waxman commended Hayward for agreeing to establish the $20bn fund, but wasted no time in slamming BP, saying safety warnings had fallen on "deaf ears".
The Californian politician told him there was no evidence of any top BP officials being briefed on possible safety issues at the Deepwater Horizon offshore drilling platform before the blast that sparked the disaster.
However, Waxman pointed to a series of warnings about what one engineer dubbed "a nightmare well" before the explosion.
"You were brought in to make safety the top priority of BP. But under your leadership, BP has taken the most extreme risks."
Hayward said: "I want to acknowledge the questions that you and the public are rightly asking. We don't yet have all the answers to these important questions.
"But I hear and understand the concerns, frustrations and anger being voiced across the country."
|Hayward said the entire oil industry needed to improve its practices [Reuters]
Executives from several other oil companies were seen to be critical of BP in congressional hearings earlier this week, portraying themselves as a cut above the London-based firm in terms of safety practices and operational standards.
But in his testimony Hayward tried to widen the circle of blame, rebuffing those claims and saying the entire industry needs to improve.
In prepared testimony he said it was too early to understand the cause of the "complex accident", adding that "a number of companies are involved, including BP," in the disaster.
Nick Spicer, Al Jazeera's correspondent in Washington, said that while the BP boss had acknowledged responsibility for the oil spill he had been very keen on pointing out the involvement of other companies.
"So in the weeks and months to come, as there are more and more lawsuits, BP, despite having agreed to set up a $20bn fund ... will be perhaps hoping to avoid paying all of the money that will be paid out, and perhaps hoping to share some of the blame and some of the financial pain," our correspondent said.