Details of SMSes and Whatsapp messagess which IT executive Cecilia Sue sent to former anti-drug chief Ng Boon Gay last year were revealed by the defence in a district court on Thursday.

Some were sent mere days after he allegedly forced her to perform oral sex on him.

The messages included "M U" - which Ms Sue said meant "miss you" - "Do you D-I-Y", "I could have spent three hours with you, had fun?" and "you ignore me, how how how?"

During defence counsel Tan Chee Meng's cross-examination of Ms Sue, 36, the court also heard about a fifth alleged tryst between the two, where they allegedly had sexual intercourse.

Referring to the first statement Ms Sue gave to the Corrupt Practices Investigation Bureau in December last year, Mr Tan pointed out that she had told CPIB investigators that she had sex with Ng at a service apartment in Great World City in 2009.

But in court on Thursday, she reneged on the facts of the statement, saying it was not true and had been given while she was under stress.

"I thought my new statements would supersede the older ones," said Ms Sue, referring to the remaining eight other statements the CPIB had recorded from her.

Ng, 46, faces four counts of obtaining oral sex in exchange for showing favours when Ms Sue was a sales manager at Hitachi Data Systems (HDS) and Oracle Corporation Singapore. He can be fined up to $100,000 or jailed for up to five years on each charge.

The defence's case has been that she and Ng were having an affair since 2009, two years before the first of the four alleged occasions he forced her to give him oral sex.