SINGAPORE - A search party of more than 70 people scoured Singapore's parks and nature areas on Sunday (Feb 19) morning in search of Mr Steward Lee, an avid hiker.

Mr Lee, 27, went missing on Friday afternoon, his sister Ms Lee Yunqin told The Straits Times.

Mr Lee left his mobile phone at home, which he sometimes does, but he always informed his family if he was staying out, Ms Lee said.

This is the first time he has gone missing.

Her family made a police report on Friday night, and the police sent out a missing person alert on its Facebook page on Saturday afternoon appealing for information on Mr Lee.

The 1.79m-tall young man was last seen at Blk 407, Fajar Rd at around 2pm on Friday. He was wearing a black t-shirt and jeans.

A witness saw him at Saujana Road at 2.20pm, Ms Lee said.

A group of friends and family members have been searching for Mr Lee since Friday night. They covered areas in Bukit Panjang and libraries, which he frequents, Ms Lee said.

On Saturday afternoon, Ms Lee posted an appeal on Facebook for volunteers to conduct a sweep of nature areas.

Mr Lee went hiking almost every day, she said.

"We think that he may be in one of the parks...but the police needs help covering the ground, especially in off-trail areas," she wrote.

The search effort today involved more than 70 people, comprising police officers, park rangers, family and friends.

Ms Lee had recruited about 60 volunteers to cover a large area including the Bukit Timah Nature Reserve, Dairy Farm and Singapore quarry area, Mandai, Zhenghua Park and the rail corridor.

The group started at 9am, but had no news as noon approached on Sunday.

She said: "We're really worried, anyone who has any information can come forward."

Members of the public with information can call the police hotline at 1800-255-0000 or submit information online at www.police.gov.sg/iwitness.