The US government is suing BP for £13.5 billion ($21.1 billion) over the Gulf of Mexico oil spill, alleging that a serious failure of the company’s monitoring systems played a leading role in the accident.

BP and its partners had failed to use the safest and best drilling technology to monitor the well’s conditions and keep it under control, the Department of Justice said in its filing yesterday in a New Orleans court.

They had also failed to keep constant surveillance on well conditions, and to properly design and maintain the technology in use, the lawsuit said.

The companies were accused of failing to “maintain control of the well”. BP and partners Anadarko, Moex Offshore, Triton Asset Leasing and Transocean had “failed ... to use the best available and safest drilling technology to monitor and evaluate the Macondo Well’s conditions and to minimise the potential for the Macondo Well to flow or kick”, it said.

The lawsuit follows a separate investigation by the US Oil Spill Commission, in which investigators have so far said BP had ignored the warnings of key cement modelling software in order to save time. BP did not comment on those allegations.

In recent weeks, a key engineer on the rig said in testimony that he had stepped away from his safety monitor to have a cigarette, missing the warning signs on screen. There are also major questions about automatic and manually controlled systems in the blowout preventer, which is supposed to prevent accidents and is being forensically analysed.

The current lawsuit also includes insurers Lloyd's of London. Halliburton, the cementing contractor has not been named. The government has said it may add more defendants in the future.

The companies named in the suit are being accused under the US Clean Water Act and the Oil Pollution Act, with up to $21.1 billion in damages being sought for the millions of barrels that leaked, on top of the $20 billion (£13.8 billion) already paid by BP into an account to compensate local businesses.

"We intend to prove that these defendants are responsible for government removal costs, economic losses and environmental damages without limitation," said US attorney general Eric Holder.

"As investigations continue, we will not hesitate to take whatever steps necessary to hold accountable those responsible for this spill."

BP said in a statement that the suit "does not in any manner constitute any finding of liability or any judicial finding that the allegations have merit".

Transocean disputed why it was included in the legal action. “No drilling contractor has ever been held liable for discharges from a well under the Oil Pollution Act of 1990.

"The responsibility for hydrocarbons discharged from a well lies solely with its owner and operator," it said. It is understood the other companies will contest the lawsuit.