AN international hunt is under way for up to 130lb of radioactive material — suitable for use in a terrorist “dirty bomb” — that brokers are trying to sell to the highest bidder in southeast Asia. Police and intelligence officials from Thailand and several western powers are helping to track down the caesium-137, which is said to be stored in neighbouring Laos. The search follows the arrest in Bangkok on June 13 of a Thai headmaster, Narong Penanam, 44, who tried to sell 62lb of the material for £150,000 to undercover Thai police working with American agents. Western officials and...