Business confidence has jumped to its highest level in four years, according to data released by BDO Stoy Hayward.

BDO's Business Trends survey shows that both confidence and output are back at pre-recession levels.

However, the report warns that a significant increase in investment in the private sector is needed to sustain the recovery otherwise business confidence could falter.

"The economy is showing signs of improvement, but the main political parties risk frittering this opportunity away if they don't provide clarity for businesses now," said Alex White, a partner at BDO.