An unidentified man has thrown a suitcase containing a small explosive device at a synagogue in central Cairo, the Egyptian interior ministry has said. 

The device, which contained cans of petrol and a bottle of sulphuric acid, exploded on Sunday without injuring anyone.

The attacker had apparently checked into a hotel across the road from the synagogue before the incident and thrown the device from a fourth-storey window, the interior miistry said.

Security forces were hunting the man, who escaped unharmed from the scene, after scraps of clothing that were left in the suitcase had been found.

There is always a heavy police presence outside the Jewish place of worship in the Egyptian capital.

The temple, known as Shaar Hashamayim, or the Gate of Heaven, was built in 1899 and services are sometimes attended by israeli diplomats.

However, most of the country's Jewish population, which once numbered about 80,000 people, left Egypt five decades ago amid hostilities between Arab countries and Israel.

Just several dozen elderly Jews are believed to remain.

In 1979, Egypt became the first Arab state to sign a peace treaty with Israel.

Egypt has been rounding up youths with alleged links to Islamist groups over the past months, reportedly amid growing suspicions that they are being recruited to carry out attacks.

In February 2009, a bomb exploded in a busy Cairo tourist area killed a French tourist, the first deadly attack on foreigners in Egypt since bombs killed at least 23 people at a resort in the Sinai Peninsula in 2006.