The sources said Muslim militants, bent on turning Egypt into a purist Islamic state, were behind both incidents. The bombs were spotted aboard a bus filled with tourists outside Cairo's medieval citadel and were removed before they could explode.
An Interior Ministry statement said Brigadier-General Mohammed al- Shaimi, the deputy head of security in Assiut province, was killed when his car was ambushed in Abu Tig, about 345km (215 miles) south of Cairo.
Shaimi, 44, was appointed to his post in Assiut - the heartland of militant unrest - only last week. He was the most senior government official to be killed since militants shot dead the parliamentary speaker Rifaat Mahgoub in 1990.