Doctors this week will seal the small hole in Prime Minister Ariel Sharon's heart that apparently led to the Israeli leader's recent stroke, Sharon's office said Sunday.

The procedure, known as a cardiac catheterization, will be performed Thursday.

The hole was discovered after Sharon's Dec. 18 stroke. The hole in the partition between the upper chambers of Sharon's heart measures less than an inch and is a congenital defect found in 15 to 20 percent of the population, doctors said.

It apparently led to the blood clot that caused his stroke, and sealing it will virtually eliminate the risk of another stroke of this type, doctors said.

Doctors said last week that Sharon suffered no lasting damage from the stroke. He was released from the hospital after two days and already has resumed his full workload.

But the health scare raised concerns about the 77-year-old leader's ability to work as he runs for a third term in March.