US Ambassador to Bangladesh Harry K Thomas yesterday said untracked faxes and e-mails have prompted the US embassy in Dhaka to issue security alert to US citizens in Bangladesh.

"Untracked faxes and e-mails which carry credible evidence for possible threats against the US embassy and the citizens of my country have prompted us to alert our people," he said on the sidelines of a three-day conference on infectious diseases in the Asia Pacific Rim here.

The government of Bangladesh has organised the conference being sponsored by the US-Japan Cooperative Medical Science Programme at a city hotel. About 150 health experts and scientists from Japan, the US and host Bangladesh are attending it.

Thomas, who joined the inaugural session of the conference as special guest, said it was his responsibility to protect the US citizens in Bangladesh. He, however, gave no details.

Health Minister Khondoker Musharraf Hossain inaugurated the conference as the chief guest, while Japanese Ambassador to Bangladesh Matsushiro Horiguchi attended as special guest.

The United States issued security alert on Tuesday based on what the State Department said the information about possible threats against its embassy in Dhaka and Americans living in Bangladesh.

Bangladesh refuted the allegation and stepped up security for foreigners. Around 5,000 foreigners live in Bangladesh and none of them came under any attack in the past.