Germanwings crash: German police seize co-pilot's belongings

German police have seized possessions belonging to a co-pilot who apparently crashed his plane in the French Alps killing all 150 people on board, as they investigate his possible motives.

They said they had found a significant clue, according to media reports.

The revelations by the German police come after officers searched Lubitz's flat in Duesseldorf and the house the 27-year-old shared with his parents in Montabaur, north of Frankfurt, late on Thursday.

A number of items were removed - including boxes and a computer - from the two properties.

"We have found something which will now be taken for tests. We cannot say what it is at the moment but it may be a very significant clue to what has happened," a police spokesman said.

However, police said the discovery was not a suicide note.

There were also unconfirmed reports in the German media that Lubitz had suffered from depression. German government officials said Lubitz was not known to the country's security services.

Data from the plane's voice recorder suggest Lubitz had deliberately started a descent while the pilot was locked out of the cockpit.

Several airlines have now pledged to change their rules to ensure at least two crew members are present in the cockpit at all times.