Two British tourists - one of them a diving instructor - helped to rescue an elderly woman from a lake in Bukit Batok Town Park on Tuesday.

The 72-year-old woman was taken conscious to Ng Teng Fong General Hospital after being rescued from the lake using a life buoy and ladder, the Singapore Civil Defence Force (SCDF) said.

Photographer Lesley Brewin, 65, and her husband were in Singapore to visit their children.

On Tuesday, they were by the lake, known as Little Guilin, when they saw a small stool beside a low wall there.

Sensing something amiss, they went to investigate and saw that beyond the wall, a woman appeared to be drowning in the lake, Mrs Brewin told Chinese-language newspaper Shin Min Daily News.

She tried to get help from passers-by, while her husband sought to find ways to bring the drowning woman back to shore.

Mrs Brewin, a diving instructor, eventually jumped into the lake to rescue the woman.

She kept the woman afloat and provided mouth-to-mouth resuscitation to her before SCDF officers arrived.

"I was focused on saving her at the time. The water was not too deep, and since I'm a diving instructor and have learnt how to rescue people at sea, I knew what to do in such emergencies," Mrs Brewin said. "I hope the woman recovers soon."

SCDF said it responded to a call for assistance at Bukit Batok Town Park at 11.50am on Tuesday and that a member of the public helped the woman.

SCDF told The Straits Times that it was looking into recognising the part played by the British tourists in helping the woman.

The police said they were alerted to a case of attempted suicide in Bukit Batok East Avenue 5.

The rescued woman was arrested in relation to the case.