A Sun executive in charge of doling out cash to reporters for their sources today said he did not know how often payments were made to public officials.

Giving evidence at The Sun corruption trial, Mr Dudman told the court that on rare occasions The Sun did pay officials for information but said he did not know how much cash went to them, saying: "I don't have the paperwork."

Mr Dudman, who faces three counts of conspiring to commit misconduct in a public office, rejected any suggestion that there was a "culture of industrial-scale corruption" at Britain's best-selling newspaper.

In answers to his lawyer, Oliver Blunt QC, Mr Dudman agreed that in 2004 the paper had paid out between £362,000 and £424,000 in cash.

Mr Dudman, who always kept £25,000 in notes in a safe in his office at News International's headquarters in Wapping, explained to the court how he would count out the cash for assistants to hand to reporters.

As the line of questioning moved on, a member of the jury passed a note containing a question to Judge Richard Marks.

The judge asked Mr Dudman the question, which began: "Cash payments seem to be about £300,000 per year. We are looking at [on the charges before the court] about £10,000 per year."

Referring to Mr Dudman's previous explanations as to why contributors might want to be paid in cash, the juror added: "Are all the other payments to members of the public who didn't have bank accounts... [or who wished to remain] anonymous – or are there other payments to public officials we don't know about?"

After a pause, Mr Dudman replied: "I don't have the paperwork. I just don't know, I'm afraid."

Mr Blunt followed up the question by asking Mr Dudman whether there was "a culture of industrial scale bribery and corruption" at The Sun."

Absolutely not true," the journalist replied.

Mr Blunt went on: "Were you aware public officials were paid?" to which his client said: "Yes, on very rare occasions."

What was the justification?, asked the lawyer.

Mr Dudman told the court: "That the material obtained was absolutely in the public interest."

He told the court that in 2005 he had imposed tighter restrictions on reporters for contacts obtaining cash because there was a concern that some were keeping some of the money themselves.

Mr Dudman, who was managing editor of the paper until 2011, said: "I think the sentiment was that there was a worry that some of the cash payments were not being spent on journalism."

There was no proof but there was... – suspicion is probably too strong a word – but there was some concern that some of the payments were being pocketed by journalists."

In answer to questions about his alleged role in paying a police officer for information about the Soham murder investigation in 2002, Mr Dudman, The Sun's Editorial Development Director, suggested that he had been fabricating his own expenses.

His QC pointed out that he made a Sun expenses claim for "allegedly entertaining a City of London police contact at the restaurant Joe Allen's" on 6 September 2002, when he was at the end of a week of paternity leave.

Mr Dudman said he did have a source for stories about Soham but said he would not identify the source because he had a moral duty as a journalist to protect his sources. "I'm really not going to answer any questions about who I was or as not entertaining," he told the court.

In answer to a question from the judge, however, Mr Dudman said: "I'd be astonished if I took one of my last days of paternity leave for a work-related lunch."

I was definitely in London dining in Joe Allen's... but I cannot remember whether it was a work related meal or whether I was using the expenses form to claim the meal back as part of my desk expenses."

The same day Mr Dudman claimed for a meal with a "BBC contact." Of that, Mr Dudman said: "It was a takeaway meal that I ate and probably ate with my wife and daughter."

He and five other current and former journalists at the Sun deny conspiring to commit misconduct in a public office. The case continues.