In the shadow of a mounting Iranian nuclear threat, Israel's largest daily newspaper reported on Thursday that Prime Minister Ehud Olmert is having a new bomb shelter capable of withstanding a nuclear or chemical missile strike built at his official residence in Jerusalem.

Several workers participating in the construction told Yediot Ahronot that the bunker is being equipped with special air filtration devices in case of a non-conventional attack by Israel's enemies.

Olmert's office later issued a statement insisting that what is being built at the prime minister's residence is a regular bomb shelter of the type found in most Israeli homes.

But the newspaper noted that the bunker underneath the building housing the prime minister's office and Cabinet meeting room was recently renovated to allow the government to continue functioning in the event of an non-conventional attack.

Yediot also reported that several years ago the Israeli government began construction on a massive nuclear bunker in the hills outside Jerusalem. That facility is expected to be completed by 2011, and will be accessible via a tunnel that leads from the government center in downtown Jerusalem.

In related news, the Israeli military this week successfully tested an upgraded version of the US-made Patriot anti-ballistic missile defense system. The Israeli improvements aimed to increase the range and accuracy of the Patriot missiles to better deal with long-range regional threats.