The £1.3bn takeover, completed in June 2012, pushed revenues for the newly integrated business up by 86% to £3.7bn (2011: £1.9m).

The company also cited underlying volume growth in corrugated box sales for the strong performance. Operating profit increased 77% to £250.9m (2011: £142m).

The company also revised upwards its expected cost savings from the acquisition, from £86m to £100m.

Group chief executive Miles Roberts said it had been a transformational year for the company.

He added: "We have made substantial operating, financial and strategic progress, following the acquisition and successful integration of SCA Packaging, providing a strong platform for further growth.

"The ongoing commitment and focus from our employees has enabled us not only to deliver the initial synergies we targeted earlier than expected, but also to identify further synergies across the enlarged business."

Roberts cited substantial earnings growth and confidence in medium-term prospects for the business FTSE 250 for a 36% increase in full-year dividend to 8p (2011: 5.9p)

The group figures were however, impacted by the depressed paper market, which resulted in a 26% decline in operating profit for its UK division.

Total revenues for the UK arm, comprising its corrugated packaging business, recycling operations and UK paper manufacturing facilities, remained flat at £961m (2011: £960m).

Roberts said: "While our core UK corrugated packaging business has delivered a robust performance, revenues for the overall UK division have been impacted by continuing weakness in the paper market, as a result of which, prices and demand have remained subdued."

Focus going forward would be to continue growing the packaging and recycling businesses, while "reducing our exposure to paper manufacturing and disposing of non-core businesses and assets", he said.

Roberts said the current financial year had started well and was in line with expectations. "Continued market share gains, together with the delivery of further synergies underpin our confidence for the future, despite the market backdrop remaining challenging and the expected impact of input cost pressures.

"Our strengthened customer proposition will be further enhanced by increased investment in capital expenditure, R&D and new business development. Looking ahead we remain excited about the further growth opportunities for the group," he added.