SINGAPORE - A jobless man admitted on Tuesday to a raft of charges under the Computer Misuse and Cybersecurity Act, most of which involved the entering of unauthorised script into the Prime Minister's Office (PMO) website on Nov 7 last year.

Abusing a Google search box embedded on the page, Mohammad Azhar Tahir, 27, created script which would generate an image referencing international hacktivist group Anonymous, when triggered.

Then on various social media websites, he posted a link containing the script, which superimposes a Guy Fawkes mask and a sentence reading "It's great to be Singaporean today" over what the site's search page would normally display.

Internet users clicking the link would form the impression that the PMO website had been defaced though data on its server had not actually been altered, leading to widespread public speculation and concern, the prosecution said.

On Tuesday, Mohammad Azhar pleaded guilty to seven of 59 charges against him, which also included illegally accessing a neighbour's wireless Internet service and modifying social media accounts that belonged to Ah Boys to Men actor Ridhwan Azman. Mohammad Azhar made use of the neighbour's connection to commit the PMO website offences, and the actor's accounts to publicise the offending script.

His brother, full-time national serviceman Mohammad Asyiq Tahir, pleaded guilty to 5 of 11 charges. These are similar to those faced by Mohammad Azhar, with the exception of PMO website offences.

Both are expected to be sentenced on Dec 8.

For each count of securing unauthorised access to the website server, Mohammad Azhar faces up to three years in jail and a $10,000 fine.