* Fourth Malaysian firm to face U.S. ban in 15 months

* U.S. finds 10 of 11 forced labour indicators

* Supermax shares fall 9%

* U.S. accounts for 20% of Supermax's total sales

* Firm appoints independent firm for audit of factories

KUALA LUMPUR, Oct 21 (Reuters) - The United States has barred imports from Malaysian glove maker Supermax Corp over alleged forced labour practices, the fourth Malaysian firm to face such a ban in the past 15 months.

Malaysian factories - which make everything from palm oil to medical gloves and iPhone components - have increasingly come under scrutiny over allegations of abuse of foreign workers, who form a significant part of the manufacturing workforce.

The U.S. Customs and Border Protection (CBP) issued a "Withhold Release Order" that prohibits imports from Supermax based on reasonable information that indicates the use of forced labour in its manufacturing operations, the CBP said in a statement on Wednesday.

"With 10 of the 11 forced labour indicators identified during the course of our investigation, CBP has ample evidence to conclude that Supermax and its subsidiaries produce gloves in violation of U.S. trade law," said AnnMarie R. Highsmith, executive assistant commissioner at the CBP Office of Trade.

The CBP was referring to forced labour indicators identified by the International Labour Organisation that include excessive hours, debt bondage, physical and sexual violence, abusive working and living conditions.

The CBP did not detail which indicators were found at Supermax.

The firm's shares fell nearly 9% on Thursday.

Supermax said it was in contact with CBP to obtain more clarity and that it will speed up a process it had begun in 2019 to meet ILO standards.

"Supermax is surprised that due consideration has not been given to the fact that corrective steps have started and improvements made to labour welfare," it said in a statement.

The company said the United States accounts for about 20% of its total sales and that it will now take efforts to divert its products to other markets.

The glove maker also said it has commissioned an independent consulting firm to conduct an audit into the status of foreign workers at its factories.

Most migrant workers in Malaysia come from Bangladesh and Nepal.

Labour rights activist Andy Hall, who filed the petition to the CBP to investigate Supermax, said his interviews with the firm's workers showed they lived and worked in "appalling conditions".

He said the workers paid high recruitment fees - which resulted in debt bondage - faced unlawful wage deductions and lived in cramped conditions.

Supermax did not respond to Hall's comments.

Supermax's bigger Malaysian rival Top Glove - the world's largest latex glove maker - was barred by the CBP over similar allegations last July. The ban was lifted last month after the company resolved the labour issues.

Palm oil producers Sime Darby Plantation and FGV Holdings have also been banned by the CBP in the last year over forced labour allegations.

Sime Darby and FGV have both appointed auditors to evaluate their practices and said they would engage with the CBP to address the concerns raised. (Reporting by A. Ananthalakshmi; editing by Lincoln Feast and Jason Neely)