BP staked its future on expanding offshore drilling a month before the catastrophic explosion on the Deepwater Horizon triggered the United States' worst environmental disaster, according to company documents revealed yesterday.

The Deepwater Horizon oil rig burning. The battle over the future of offshore drilling continued yesterday as the country's biggest business lobby said it would step up its campaign to force the Obama administration to lift its six-month ban on drilling new wells in the Gulf of Mexico. (Photograph: Gerald Herbert/AP) The investigative web site ProPublica published a March 2010 strategy document in which BP named "expanding deepwater" as its number one area for long-term growth.

But even as the document was drawn up, engineers were struggling to control the Macondo well in the Gulf of Mexico, which had already gained a reputation as a risky operation, according to industry sources.

The strategy paper claimed BP now held a global lead over its competitors in deepwater production – even though its costs were considerably lower. Earlier this month the executives of BP's rivals, including Exxon and Chevron, told a congressional hearing they would have taken more safeguards on the doomed Deepwater Horizon rig.

The battle over the future of offshore drilling continued yesterday as the country's biggest business lobby said it would step up its campaign to force the Obama administration to lift its six-month ban on drilling new wells in the Gulf of Mexico.

The Chamber of Commerce, which has strenuously fought efforts to introduce climate change legislation, said Obama's decision to halt new projects for an overhaul of safety regulations had had a "chilling" effect on the Gulf economy.

"We must avoid snap decisions following the spill that would threaten US energy security and harm our economy," Karen Harbert, a Chamber official, said.

Meanwhile, there was fresh speculation about the professional future of BP's chief executive after a senior Russian cabinet minister reportedly said he was expecting Tony Hayward to introduce a successor during a scheduled meeting in Moscow.

And the first hurricane of what is expected to be a very active season in the Gulf began moving up towards north-western Mexico and Texas. Forecasters said Tropical Storm Alex was likely be upgraded to a hurricane tomorrow.

It is expected to pass well to the west of the site of the ruptured well, but the disturbance could still set back efforts to contain oil from the gusher and to drill a new relief well for as much as two weeks, the coastguard said at the weekend.

Officials said they would pull out heavy equipment and clean-up personnel from the area around the ruptured well if forecasts suggest the approach of a storm with winds higher than 46 miles per hour

The potential for delays in clean-up operations comes at a critical time. BP officials say the relief well seen as the only surefire way of containing the gusher is within 20ft, horizontally, of the ruptured well.

BP's senior vice-president Kent Wells said engineers were going to drill an additional 900ft down before trying to intersect the ruptured well with heavy mud. He indicated it would take time to bridge that seemingly short distance. BP has said it hopes to complete the relief well by August.

"This is the point in time we have to be very good at what we're doing," Wells said.