Officials and experts will spend the next four to six months studying the data gathered in the five-day anti-terrorism game that ended on Friday, senior officials with the US Homeland Security Department said Friday.

They would identify lessons learned and write a report on the game, "the largest, most complex, comprehensive and dynamic exercise counterterrorism-wise" in the United States, they told reporters.

US security officials began the exercise, named "TOPOFF 3," in the eastern states of Connecticut and New Jersey on Monday, to train first responders with fake biological and chemical terror attacks.

According to the plan of the exercise, terrorists who had plotted to attack New York and Boston and suspected their plans had been compromised launched a premature attack by dispersing a biological agent from a car in New Jersey and a chemical attack in the town of New London, Connecticut.

More than 10,000 people from as many as 275 federal, state, local and private sector agencies and nongovernmental organization participated in the 16 million-US dollar event, both in the planning and execution phases. Canada and Britain conducted related exercises simultaneously in their own countries, and 13 countries, including Singapore, France and Australia sent observers to the drill.

The officials listed four major objectives for the game: to test the ability to manage and respond simultaneously to two weapons of mass destruction-related attacks; to test the handling and flow of information-sharing across all levels of government and the private sector, as well as with Canada and Britain; to test public communications strategies, protocols and processes; and to identify lessons learned and promote best practices.

"TOPOFF 3" is the third of a series of Congress-mandated exercises conducted by the Department of Homeland Security involving simulated terrorist chemical, nuclear or biological attacks. The first was held in May 2000 and the second in May 2003.