A team of Israeli and US scientists say new tests on comatose former Prime Minister Ariel Sharon show significant brain activity.

Ben-Gurion University on Sunday said Sharon responded to external stimuli at Soroka Hospital in Beersheba.

He was shown pictures of his family and listened to recordings of his son's voice while undergoing a special brain imaging scan. The university said "significant brain activity was observed ... indicating appropriate processing of these stimulations."

However, Sharon remains in a deep coma.

Sharon, 84, led Israel from 2001 until suffering a stroke in 2006. Since then, he has been in a vegetative state, connected to a respirator.

Sharon was a storied military officer who fought in three wars before entering politics. He unilaterally withdrew Israeli troops and settlers from Gaza in 2005.