US president Barack Obama said he was enraged that BP has failed to halt the flow of oil from the worst spill in the country’s history.

Six weeks after the catastrophe began, the oil company is trying to find at least a temporary fix to the spewing well 5,000ft down in the Gulf of Mexico.

Relief wells being drilled, which are supposed to be a better long-term solution, will not be ready for at least two months.

BP said engineers tried in vain for three days to overwhelm the crippled well using heavy drilling mud and junk 5,000ft underwater.

President Obama, who visited the Gulf Coast at the weekend to see the damage the oil is causing to beaches and marine life, said: “It is as enraging as it is heartbreaking, and we will not relent until this leak is contained, until the waters and shores are cleaned up, and until the people unjustly victimised by this manmade disaster are made whole.”

Robert Dudley, BP’s managing director, said company officials were disappointed that they have “failed to wrestle this beast to the ground”.

Scepticism is growing that BP can solve the crisis.

Republican Ed Markey, who leads a congressional committee investigating the disaster, said he had no confidence in BP.

The company now hopes to saw through a pipe leading out from the well and cap it with a funnel-like device using remotely guided undersea robots. However, officials said that would not stop all the oil escaping.

The spill is the worst environmental disaster in US history – exceeding even the 1989 Exxon Valdez disaster – and has dumped between 18 and 40 million gallons into the Gulf, according to government estimates.

The leak began after the Deepwater Horizon drilling rig exploded on April 20, killing 11 people.

BP chief operating officer Doug Suttles said: “This scares everybody, the fact that we cannot make this well stop flowing, the fact that we have not succeeded so far.

“Many of the things we are trying have been done on the surface before, but have never been tried at 5,000ft below the surface.”