Executives at the oil giant BP repeatedly ignored safety warnings over three years and ordered budget cuts at its Texas City refinery in the US, which exploded, killing 15 workers and injuring hundreds more, an investigation into the disaster says.

	John Manzoni was BP operations chief at the time of the explosion

The damning report, published yesterday, directly implicates the BP board, saying that "at least one" executive received a series of safety audits warning of problems at Texas City. The report from the US Chemical Safety Board (CSB) says it will not name names because it "does not affix blame". John Manzoni was head of refinery operations at the time.

The CSB's conclusions are more critical than expected and will fuel litigation and prompt calls for further changes at BP. The company said yesterday it strongly disagreed with some of the conclusions and recommendations, but declined to spell out its objections.

BP maintains that its board of directors have no "unique" knowledge of the explosion or its causes, which is why its chief executive, Lord Browne, has resisted attempts by US lawyers to force him to testify. The report is likely to be seized on lawyers in their continuing attempts to force a statement from Lord Browne

The 335-page report says: "Decisions to cut budgets were made at the highest levels of BP despite serious safety deficiencies at Texas City." Cost-cutting, it says, "left the refinery vulnerable to a catastrophe."

From 2002, BP executives received seven safety audits and studies, all warning of mounting safety risks at the Texas facility, the CSB said: "These were shared with BP executives in London, and were provided to at least one member of the executive board \u2026 BP's response was too little and too late."

The CSB found BP ordered across-the-board budget cuts of 25pc in 1999 and again in 2004 after receiving escalating safety warnings and three fatal accidents at the Houston refinery before the blast in March 2005.

The explosion, caused when faulty equipment meant petrol vapours escaped and ignited, was the worst industrial accident in the US since 1990. It led to a record $21m (£10.7m) fine for safety violations, and more than 1,750 lawsuits, and probably contributed to Lord Browne bringing forward his retirement date. BP has admitted lapses at the refinery, its largest, and set aside $1.6bn for claims.

CSB investigators found such basic safety threats as broken alarms, improperly calibrated gauges and dirt-encrusted dials. Before the explosion, supervisors ordered workers to restart the equipment without completing a safety checklist, the report says. It said: "A check-the-box mentality was prevalent at Texas City, where personnel checked off on safety policy and procedural requirements even when those requirements had not been met."

BP said it has accepted responsibility for the blast and has "worked diligently to provide fair compensation, without the need for lengthy court proceedings, to those who were injured and to the families of those who died... Notwithstanding the company's strong disagreement with some of the content of the CSB report, particularly many of the findings and conclusions, BP will give full and careful consideration to the recommendations."

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