The Singapore Medical Council (SMC) has defended itself against criticism that it takes too long to probe complaints against doctors.

It was taken to task last month by the Supreme Court for the more than five years it took to deal with a complaint against private cancer doctor Ang Peng Tiam.

An SMC spokesman told The Straits Times that cases can be complex, as in Dr Ang's case. As such, he said "this timeline is not unusual".

SMC's annual report for 2016, released last month, showed its Complaints Committee (CC) processed 386 cases last year, including a complaint lodged in 2011, seven in 2012, 14 in 2013, and 63 in 2014.

There were 182 complaints made last year against 242 doctors, 41 more than in 2015. Although the CC dealt with 386 cases, there were still 247 cases yet to be looked at.

Explaining the time it takes to deal with complaints, the spokesman said: "Given the serious nature of many complaints, investigations by a CC usually take at least nine months. For even more complex complaints, investigations may take more than a year."

For example, if the complainant provides new information that must be looked at.

The spokesman added that after a CC has completed its inquiry, both parties have the right to appeal to the Minister for Health if they are unhappy with the verdict. The minister might then direct the CC to investigate the complaint further.

"This will naturally result in a longer period of time taken to dispose of a complaint, as the CC's investigations are carried out over two separate tranches," he said.

But Dr Chia Shi-Lu, head of the Government Parliamentary Committee for Health, said: "I think many of us agree that the workings of the SMC can be more robust and streamlined."

He added: "The recent cases that have troubled SMC have made them even more cautious and this has affected expediency."

In Dr Ang's case, the complaint was made against him in 2010, but the disciplinary hearing was concluded only last year.

Describing the delay as "inordinate", Chief Justice Sundaresh Menon said in the Supreme Court judgment on June 27: "Even if the SMC had difficulty finding expert witnesses locally as it says it had, it was open for the SMC to have begun its search for expert witnesses overseas much earlier."

One member of the Disciplinary Tribunal had recused herself and it took a year for the SMC to set up a second tribunal.

Chief Justice Menon said: "The SMC carries a regulatory and adjudication function affecting the professional livelihood of doctors. We stress... that the SMC must approach the prosecution of disciplinary cases with due expedition and care."

Because of the long delay, the court halved Dr Ang's penalty from a suspension of 16 months to eight months.

The CC is drawn from a group of more than 160 doctors and lay people. Of the cases the CC handled last year, letters of warning were issued to seven doctors, and letters of advice to 39. It dismissed 71 complaints and referred 14 to disciplinary tribunals, and one doctor to a health committee.

The SMC annual report also gave an update on the number of doctors here, which has grown to 13,478 last year, up from 13,006 in 2015. More than 2,000 are foreigners, and 3,725 are Singaporeans and permanent residents who were trained abroad and returned to work here.