The website of pre-school chain Carpe Diem, which was hacked on Sunday, has been restored on Monday afternoon.

When The Straits Times logged on to the website at 2 pm on Monday, it was functioning normally.

Manager of Carpe Diem Holdings Doris Tan said the information technology department worked to rectify the issue immediately when they were informed of the hacking incident on Monday morning.

She added that the pre-school chain did not make a police report.

"But I will be meeting the IT department with the centre director soon to discuss how to ramp up our website's security," she said.

The pre-school chain's website was defaced by someone who signed off as Dowen on Sunday. At about 10am on Monday, the website still showed an illustration of US President Barack Obama, with a noose around his neck.

Ms Tan added that the Carpe Diem's website was last hacked in January. No police report was made then.

On Sunday, the website of Seletar Airport was also hacked and was down for 30 minutes. At about 12.30pm on Sunday, the website showed a black and green background with an image in the middle resembling a skull wearing a hood.