Mas Selamat Kastari, alleged to be the commander of the Singapore wing of Jemaah Islamiyah - a group blamed for a string of regional attacks - escaped from a detention centre on February 27 after asking to go the toilet.
He was accused of plotting to hijack a plane in order to crash it into Singapore's Changi Airport in 2001, but was never charged.
In his first statement on government accountability in the escape Singapore's prime minister urged people not to "over-react to one bad incident".
Opposition politicians as well as members of Lee's own ruling party have called for heads to roll over the escape.
'Not to blame'
Speaking in parliament on Tuesday Lee admitted that Mas Selamat's escape could have been prevented and "should never have happened", but "the minister and top management were not to blame for what has happened".
|Mas Selamat, who is 47 and walks with a limp, |
escaped through a toilet window [Reuters]
Singaporeans should not go on "a witch-hunt which would damage and demoralise our intelligence and security agencies", he said.
"Because if you generate a culture where nobody wants to make mistakes and they are afraid to do something for fear of making mistakes, that … would be the biggest mistake of all."
He said Wong, who is also a deputy premier and the director of the internal security department charged with holding Mas Selamat continued to have his full confidence.
"We must admit our mistakes openly and honestly, put them right and act against those who have been culpable," Lee said, "however senior his position".
"But if he is not at fault, then we must have the moral courage to state so, and support him. This way, everybody within the organisation can be confident that when something goes wrong, they will not be sacrificed for political expediency."
Lee said he was satisfied that remedial and disciplinary action had been taken to prevent another escape.
The escape of Indonesian-born Mas Selamat triggered an ongoing manhunt across Singapore and neighbouring South-East Asian countries.
Security officials have said recently they still believe he is hiding out in Singapore and say he remains dangerous.
A panel investigating the case said surveillance cameras that were not working and slow reaction by guards contributed to his escape.
Mas Selamat had been held without trial since March 2006 after Indonesian authorities arrested him and handed him over to Singaporean authorities.