The website showed the message: "MrCreepy Was Here. Napsters CrEw. Happy Independence Day Pakistan. Greets: SEEKER, Dr.FREAK, MKHAN SWATI, And All Pakistani Hackers :D".
However, the corporate website of the telecom services provider, which has over 80 lakh customers, and its portal for Delhi customers were not affected.
In a post on social networking website Facebook, the hacker 'MrCreepy' also claimed to have attacked the websites of Pune Traffic Police and janwani.org (a voluntary group).
Another post, dated August 14, stated "Lol Just rooted MTNL Server, feeling excited".
However, the websites of Pune Traffic Police and janwani.org were found to be working normally.
In June last year, MTNL's corporate website was disrupted by hacker group "Anonymous" to protest against "censorship" of the Internet. However, city-specific websites (for Delhi and Mumbai) were not attacked then.