Mr Sharon announced his building plans a day after the Prime Minister, Benjamin Netanyahu, said he supported the expansion of settlements in the West Bank and Gaza Strip.
The Palestinians, who want to establish a state in the West Bank and Gaza, say expanding settlements violates the Israel-Palestine Liberation Organisation accords and could bring the peace process to a halt.
Freih Abu Medein, the Palestinian Justice Minister, predicted violence would follow if Mr Sharon was given a free hand on settlements.
Mr Sharon said the roads would ease traffic congestion and would be used by both Israelis and Palestinians. His plan calls for one road from the West Bank into northern Jerusalem and a second linking central Israel with Jewish settlements inside the West Bank.