Former law professor Tey Tsun Hang was sentenced to five months jail by Chief District Judge Tan Siong Thye on Monday.

Tey sat stone-faced as his sentence was read out by the judge. He was later led away in handcuffs to the Subordinate Courts lock-up, but is expected to be released on bail - which has been raised to $150,000 from $100,000 - later in the day.

He told The Straits Times before the start of proceedings earlier that he had been "distressed" by the court's judgment and plans to appeal against his sentence.

Tey was found guilty last Wednesday on all six counts of corruptly obtaining sex and gifts - a Mont Blanc pen, an iPod, two tailored shirts, and dinner at Garibaldi Italian Restaurant & Bar - from his former student Darinne Ko. He was also ordered to pay a fine of $514.80, which is the value of the two tailored shirts and part of the cost of the dinner Ms Ko paid for - and to have the pen and iPod forfeited.

Chief District Judge Tan noted in sentencing Tey that the 42-year-old was "unbecoming" of a senior educator, having "clearly and systematically" taken advantage of the student.

Another aggravating factor was the "litany of lies" told by Tey, who also "behaved insidiously" from the start of the corruption probe to the end of the sex-for-grades trial.

He added that a fine, as submitted by Tey's lawyer last week, would not be appropriate as it would "trivalise the severity" of the case and it was an "irony" that these crimes took place at the law faculty of the National University of Singapore (NUS).

Tey, who was sacked by NUS on the day he was convicted, could have been jailed for up to seven years and fined up to $100,000, or given both for each charge.