By Serajul Quadir
DHAKA (Reuters) - A suicide bomber injured two Bangladeshi police officers on Friday when he attacked a base being built for the police anti-terrorist unit, officials said.
Local media quoting the BBC Bangla service said Islamic State had claimed responsibility for the rare attack on Bangladesh's security services.
Senior Dhaka police official Krishna Pada Roy said police were investigating the incident. It occurred a day after four people linked to a deadly cafe attack in the capital last year were killed when their suicide vests exploded during a raid in the southeastern town of Chittagong.
The injured police officers were taken to Dhaka's military hospital.
Mufti Mahmud Khan, director of the Rapid Action Battalion (RAB), told reporters that a man aged about 25 had blown himself up when challenged as he tried to enter the police special security force's base, which is still under construction.
Initial evidence suggested he was a member of an extremist group, Khan said.
The bomb was homemade but very powerful, he said. Police had recovered another bomb from inside a bag carried by the bomber.
Police said there could have been many more casualties if the bomber had not struck while most base staff were at the mosque for Friday prayers.
The RAB base is located in a secure area of the capital city, close to several army barracks.
Civil aviation and police officials said airports and prisons had been put on alert and security stepped up across the country. Interior minister Asaduzzaman Khan said the situation was under control.
Ishfaq Elahi Chowdhury, a retired air commodore and security analyst, said Friday's attack on counter-terrorism forces was "a new dimension" in the fight against Islamist militancy in Bangladesh.
Suicide attacks in the country are rare but there have been major incidents such as the attack in July last year on a Dhaka cafe in which 22 people, mostly foreigners, were killed.
Separately, Prime Minister Sheikh Hasina urged parents on Friday to remain alert to the risk of their children becoming radicalized.
(Editing by Catherine Evans)