A satellite image company said on Thursday that the sheer number of images covering a large swath of ocean contributed to a delay in revealing what could be debris from the Malaysia Airlines jetliner that has been missing for nearly two weeks.

DigitalGlobe Inc, a Colorado-based company that collects imagery for the US government and other countries, as well as private companies, confirmed on Thursday that it had collected satellite images on March 16 that appeared to show debris that may be related to the disappearance of Malaysia Airlines Flight MH370.

It said it provided the images to Australian authorities, who released them earlier Thursday.

DigitalGlobe said the Australian government had begun combing through the imagery of the current search area only in the last few days, after the massive international effort was expanded to the southern Indian Ocean region and waters near Australia.

Malaysian officials described the images as a credible sign of a possible wreckage from the flight, which left Kuala Lumpur on March 8 en route to Beijing with 239 people aboard and vanished after about an hour of flight.

Australian authorities cautioned that the debris in the pictures might not be related to the missing plane.

"Given the extraordinary size of the current search area, the lengthy duration of the analysis effort was to be expected," DigitalGlobe spokesperson Turner Brinton said in a statement.

Brinton said the company's five high-resolution satellites capture more than 3 million square kilometers of earth imagery each day. "This volume of imagery is far too vast to search through in real time without an idea of where to look," he said.

The large objects that Australian officials said were spotted by satellite four days ago are the most promising find in days as searchers scour a vast area for the plane.

The larger of the objects four days ago measured up to 24 metres (79 ft) long and appeared to be floating in water several thousand metres deep, Australian officials said. The second object was about five meters (16 feet) long.

Brinton declined comment on whether the debris was spotted by DigitalGlobe's own analysts, government analysts or Internet users participating in a "crowdsourcing" effort launched by the company to help locate the plane.

Brinton said the images were captured on March 16 by the company's Worldview-2 satellite at a resolution of about 50 cm, and the company was continuing to collect imagery over the area where the possible debris had been spotted.

DigitalGlobe said it had been collecting images over a broader area than the official search area, while focusing the efforts of its crowdsourcing volunteers on the search areas identified by authorities. "The efforts of millions of online volunteers around the world allowed us to rule out broad swaths of ocean with some certainty," Brinton said.

- Reuters