An internal report into how the oil giant BP monitors its refinery and chemical sites has revealed at least two near-miss accidents that could have caused deaths.

The report, leaked to Greenpeace, concludes that “urgent attention” is required to improve how BP manages crucial engineering data across the world and that the company lags behind its competitors including Shell, Chevron, Petronas and ConocoPhillips.

One serious near miss was at BP’s huge oil refinery in Whiting, Indiana, in 2014, where failures to record data properly led to $258m in lost production, the report found. Another was at BP’s chemical plant in Hull, UK, where a piece of equipment was not operated correctly, causing damages of $35-45m, while another failure saw critical blueprints that “had gone missing during critical operational activities”.

BP has suffered serious accidents in recent years, including the Deepwater Horizon explosion in the Gulf of Mexico in 2010, which killed 11 people, and an explosion at its Texas City refinery in 2005, which caused 15 deaths.

The internal report, produced in August 2015, said “inadequate management and use of engineering information has been a root cause or contributing factor in 15% of the last 500 incidents”.

“It is clear that BP have again failed to act on [earlier] recommendations and address the issues raised,” said Prof Robert Bea, a safety expert at the University of Berkeley who produced reports for BP after explosions at its Grangemouth facility between 1987 and 2001. He told Greenpeace: “These failures could have very serious effects on the safety of the refinery operations.”

A spokesman for BP said: “BP is committed to safe, reliable and compliant operations. With that in mind, BP regularly conducts internal assessments in an effort to make improvements to its operations. This particular report focused on potential enhancements to how BP manages engineering data. It is not an analysis of any operational incidents, and any suggestion that this report indicates BP is wavering from its safety commitment is wrong.”

The internal report named a series of incidents including one at BP’s chemical factory in Geel, Belgium, where crucial relief valves were found to be missing or fitted with the wrong parts.

At BP’s oil refinery at Cherry Point, in Washington state, US, the report said there is no “single aggregated list of safety critical equipment and there have been instances where getting replacement equipment up and running was compromised due to incomplete data. Response time to failure is compromised by the various sources of data. This is seen as a significant concern during a response crisis.” Five years earlier the plant had been penalised for 13 serious safety violations, including failure to keep records.

The report also found 80% of BP staff working with engineering information did not believe it “is given adequate priority or resource to be safe, reliable and efficient”. It said 7,000 engineering information users in the company “waste up to an average of an hour a day finding, using and maintaining engineering information”.

BP made its first major investment in the Gulf of Mexico since the Deepwater disaster earlier in December. But the Democrat representative Raúl Grijalva, who sits on the House of Representatives Committee on Natural Resources, told Greenpeace: “BP’s attitude seems to be that disasters like the Deepwater Horizon oil spill are the cost of doing business, which tells me we need to crack down even harder than I thought. No company with BP’s international reach should be able to shrug at safety and maintenance issues and pass on the very high costs of their indifference to the rest of us.”

The BP spokesman said: “Over the last five years, BP’s safety record has steadily improved. The company’s total number of Tier-1 process safety events – the most consequential events involving an unplanned or uncontrolled release of materials – continues to fall and is below the average for the industry.”