The group claimed responsibility for the attack. All content on the site has been replaced with: "FEEL SOME SHAME ADMIN" and a warning which reads: "WE GAT ACCESS TO OTHER HIGH RANKING NIGERIAN GOVERNMENT SERVERS BUT WE ARE NOT HERE FOR THAT TODAY!"
The hacking coincides with the presidential polls of Africa’s most populous nation.
Voting is currently underway in the oil rich country with incumbent President Goodluck Jonathan of the PDP and former head of state Mahamudu Buhari of the APC being the lead contenders.
Voters have to validate their voting cards using a fingerprint reader.
But technical problems with some readers are causing delays.
President Jonathan tried for some 50 minutes to register in his home village of Otuoke.