As the White House said President Barack Obama would travel to the Gulf coast again Friday, Allen hailed the latest effort to contain the oil pollution in one of the worst U.S. environmental disasters as "a significant step forward."
After a steep fall Tuesday, BP shares rose in London trading Thursday on market hopes the latest plan would succeed. In early afternoon, they were up about one percent.
"We have just cut the riser pipe off of the lower marine riser package," Allen told a news briefing.
This will allow the company to collect at least some of the leaking oil in a containment cap and bring it to the surface.
Gushing oil has devastated the ecology and economies of Gulf coast states and highlighted the powerlessness of the Obama administration to resolve the crisis.
BP's decision to hold a conference call with financial analysts Friday also buoyed the company's shares. Two U.S. senators said BP should suspend plans to pay shareholder dividends until spill clean-up costs are known.
"We believe BP will bow to political pressure in the U.S. and suspend dividend payments for the remainder of 2010," said a research note from London-based investment bank Evolution Securities.
Thousands of fishermen, shrimpers and other seafood workers have been idled for weeks by government-imposed fishing restrictions that cover 37 percent of U.S. federal waters in the Gulf.
Obama, accused by critics of being too slow to respond to the spill, says the government has deployed a massive federal response to contain oil before it hits land and clean-up coastlines. That is not enough for many affected residents.
BP could face billions of dollars in fines and penalties if a Justice Department investigation finds wrongdoing, in addition to billions from the economic liability and damages, according to legal experts.
It may also find it more difficult to meet targets for expanded production in the future, analysts said.