SEOUL, Nov 27 (Reuters) - Samsung came under renewed criticism from a rights group on Tuesday for illegal work practices at its Chinese suppliers, a day after the South Korean electronics giant admitted excessive overtime and fines for employees in China.

A number of foreign companies have been accused in recent years of improper labour practices in China, seen as a cheap source of labour for their production lines.

New York-based China Labor Watch (CLW) said employees at one of Samsung's suppliers sometimes worked up to 16 hours a day, with only one day's rest a month.

Samsung Electronics Co, the world's largest maker of cell phones and televisions, said on Monday a review of 105 of its Chinese suppliers - involving more than 65,000 employees - found illegal work practices, but said the companies involved would be given two more years to change their ways.

The audit followed allegations by CLW in August that seven children younger than 16 were working in one of Samsung's suppliers in China.

Samsung said the audit had found no evidence of child labour.

It did, however, concede several instances of inadequate practices, such as overtime hours in excess of legal regulations and the imposition of a system of fines for tardiness or absence.

"We have identified the need for initiatives to reduce employee overtime as a top priority, and we are researching and developing measures that will eliminate hours beyond legal limits by the end of 2014," the company said in a statement.

AUDIT RELIABILITY QUESTIONED

China Labor Watch said on Tuesday a follow-up investigation found that workers usually work from three to six times the legal overtime limit.

"The worst situation is in a Samsung supplier factory called Chitwing Mould Industry (Dongguan) Co., Ltd, where workers' overtime hours surpass 220 hours per month. Workers here can work up to 15 or 16 hours per day with perhaps one day of rest per month," CLW said in a statement.

"Samsung uses an audit system to monitor factories, but audits are renowned for their lack of reliability. Instead of audits, Samsung should establish direct channels of communication with its workers, such as worker committees or a worker hotline."

Samsung said on Tuesday hotlines were being set up for workers at supplier firms to report anonymously any inhumane treatment or violations of labour laws.

Samsung is reviewing 144 more suppliers in China and said the review would be completed by the end of this year.

The firm also said that from 2013 audits of its 249 suppliers in China would be conducted by an independent third party.

The move reflects a growing attention on work practices in China by foreign multinationals including Apple.

Apple Inc and its main contract manufacturer Foxconn Technology Group, whose subsidiary Hon Hai Precision Industry assembles Apple devices in China, earlier this year agreed to tackle violations of conditions among the 1.2 million workers assembling iPhones and iPads. That landmark decision could change the way Western companies do business in China.