The Prime Minister's Office (PMO) in Bangladesh says it has traced an Indian IP (Internet Protocol) address used for hacking 20 district portals, but acknowledges that the real identity of the hacker could be concealed.

The hacked sites were operated by the PMO and the incident is considered to be a serious security lapse.

'We have initially detected an Indian IP address that belongs to Videsh Sanchar Nigam Limited (VSNL), one of the largest Internet service providers in India,' said S.M. Akash, media manager of Access to Information (A2i) team of the PMO.

Professional hackers, however, use various methods to hide their real IP address and location, The Daily Star quoted him as saying.

The Bangladesh government will ask VSNL for details of the IP address and the hacker's location, said the official.

Twenty district websites operated by the PMO were hacked Saturday.

Some Hindi letters and 'JAI HIND!' were posted on the hacked websites.

The hackers claiming to be Indians threatened Bangladesh with a cyber war if any Pakistani terrorist enters India via Bangladesh.

Home Secretary Abdus Sobhan Sikder said they restored the websites Saturday night.