DUBAI, March 8 (Reuters) - In an effort to provide more jobs to Saudi Arabian citizens, the kingdom will ban foreign workers from selling and maintaining mobile phones and accessories for them, the Ministry of Labour said on Tuesday.

Stores selling mobile communications devices will have to ensure that at least 50 percent of staff doing such work are Saudi citizens in three months' time, the ministry said. Six months from now, the required ratio will rise to 100 percent.

The government is under heavy pressure to create more jobs for Saudis as the economy slows because of low oil prices, threatening to boost unemployment, which was officially 11.5 percent among local citizens last year.

The vast majority of jobs in Saudi Arabia's retail and services sectors are currently held by foreign workers from southeast Asia and the Indian subcontinent; they are generally paid much lower wages than Saudi citizens.

Some jobs such as human resources managers and security officers have long been reserved for Saudi nationals, but the ministry's decree suggests the government is now willing to intervene more aggressively in the labour market to get Saudis into work.

State funds will be used to support companies facing higher costs because of the decree, the ministry said.

(Reporting by Andrew Torchia; Editing by Gareth Jones) ((; +9715 6681 7277; Reuters Messaging: