AP MOLLER MAERSK chief executive Nils Smedegaard Andersen, 53, was clearly back at work with the announcement of Danish shipping giant's quarterly results after he spent more than four months on medical leave following heart surgery.

Mr Andersen was hospitalised during a skiing holiday in Switzerland in December, reported Dow Jones. After surgery to replace a cardiac valve in Switzerland for two weeks, he returned to Denmark in mid-January.

He was initially expected to resume work at the beginning of February, but suffered a setback and further surgery in late March, said the report.

"Having participated in a number of meetings and having been updated on our activities during the last couple of weeks, I am now ready to return to work," Mr Andersen said.

During his absence, the company has been led by members of the executive board, reporting to supervisory board chairman Michael Pram Rasmussen.