The six-month jail sentence given to former Singapore Civil Defence Force (SCDF) chief Peter Lim Sin Pang was "excessive", said his lawyer Hamidul Haq on Thursday.

Mr Haq was speaking to reporters outside of the Subordinate Courts after filing his client's appeal against the sentence delivered by District Judge Hamidah Ibrahim earlier in the day.

"The decision that came out from the court, obviously appears in our view, to be on the excessive side, so certainly it is disappointing but we'll definitely do our best to ensure that justice prevails in the end."

Lim was convicted of one count of corruption for his sexual encounter with Ms Angie Pang Chor Mui, 49, in exchange of furthering the business interests of her then-employer Nimrod Engineering.

But in total, the 53-year-old faced ten charges of corruption, two of which were stood down and seven others taken into considered during his sentencing.

This after he had admitted at a hearing last Friday, to seven other trysts with two other women - Ms Esther Goh Tok Mui and Ms Kelly Lee Wei Hoon, both in their 40s. They were working for information technology firm NCS and technology company Singapore Radiation Centre respectively, both of which were vendors of the SCDF.

Lim bowed his head and slumped in his seat after his sentence was read out by the judge. He remains on court bail pending a date for his appeal to be heard.

District Judge Hamidah said earlier that the fact that Lim was a first offender with no antecedents is "of little mitigating value" as "all civil servants, especially those in senior positions, are expected, in the first instance to be of good character".

But she took note that he had contributed to the SCDF and the wider society, along with the fact that he had "cooperated substantially" with the authorities.

"The information provided by the accused, such as the location and timing of the fellatio, was useful and relevant," she said.

The judge, however, also agreed with prosecution that his actions were premeditated and had caused "intangible harm" in the form of public disquiet and damage to SCDF reputation. "The fact that the accused's actions did not result in the obstruction of justice is at best a neutral factor, which in no way detracts from the severity of the offence he committed as a high-ranking public official."