US drug-maker Purdue Pharma has filed for bankruptcy protection, as part of efforts to deal with thousands of lawsuits that accuse the firm of fuelling the US opioid crisis.

The company's board approved the Chapter 11 filing on Sunday.

The move is designed in part to resolve more than 2,600 lawsuits filed against Purdue over its alleged role in the opioid epidemic.

Last week, the firm reached a tentative deal to settle most of those lawsuits

Purdue had been facing legal action from thousands of cities and counties across the US. The lawsuits claimed that Purdue and its owners, the billionaire Sackler family, had aggressively marketed the prescription painkiller OxyContin, while at the same time misleading doctors and patients over addiction and overdose risks.

The drugmaker has reached a deal with 24 states and five US territories, but another two dozen states remain opposed to the proposed settlement.

In a statement reported by Reuters, members of the Sackler family said: "It is our hope the bankruptcy reorganisation process that is now under way will end our ownership of Purdue and ensure its assets are dedicated for the public benefit."