JERUSALEM (Reuters) - Israeli bulldozers began laying the groundwork Monday for construction of a barrier to seal off part of the Jewish states border with Egypt, the defence ministry said. Israel wants to stop illegal migrants from Africa entering the country via Egypts Sinai desert, and to block the smuggling of drugs and weapons. The desolate Sinai is used as a transit route by African migrants seeking work or asylum in Israel. They are usually guided to the border for a price by local Bedouin. Egyptian border troops have shot dead at least 28 migrants this year before they could cross. We are currently working to secure 140 km (88 miles) of the 250 km (156-mile) border and it will include both a physical barrier and electronic early- warning scanners, Udi Shani, a top defence ministry official, told lawmakers Monday. Israeli government spokesman Mark Regev said Israel was constructing the barrier to protect its citizens and stop the illicit importation of drugs ... people smuggling and ... the infiltration into Israel of terrorists who want to kill our people. Heavy earth-moving equipment started work on several stretches of the border. The project is expected to take over a year to complete at a cost of about $370 million, the defence ministry said. A barrier that would secure the entire border still requires government approval and could see the cost of the project rise to about 4 billion shekels (over $1 billion).