Japan's defense chief on Friday called for tougher antiterrorism measures following the deadly bombings in Madrid, while the top government spokesman vowed to close any loopholes in Tokyo's security apparatus.

It is not yet clear who carried out the bombings in Spain, which killed more than 190 people and injured 1,400. Although the government initially blamed Basque separatists, another group claimed responsibility in the name of the al-Qaeda terrorist network.

Like Spain, Japan is a firm supporter of U.S. antiterrorism efforts and the U.S.-led invasion of Iraq.

Despite some domestic opposition, Tokyo is in the process of dispatching around 1,000 troops on a humanitarian mission to the southern Iraqi city of Samawah.

Japan last month tightened security at hundreds of locations, including airports, nuclear plants and government facilities, to guard against terror attacks, putting the country on its highest level of alert since Iraq was invaded last March.

In November, an alleged al-Qaeda operative threatened to attack Tokyo if it sent troops to Iraq.

Asked about the Spain bombings, Defense Agency Director General Shigeru Ishiba told reporters Friday that additional security steps could be taken in Japan.

Chief Cabinet Secretary Yasuo Fukuda meanwhile said there were no immediate plans to change Japan's security stance, but he suggested that officials were reviewing their current measures to see if further steps were warranted. (The Associated Press)