The economic output of Gauteng was expected to grow significantly in the next three years, the provincial department of finance said on Tuesday.

"The provincial economy has transformed into a sophisticated structure, with the tertiary [service industry] sector and the manufacturing sub-sector taking centre stage," said spokesman John Sukazi in a statement.

Gauteng's Provincial Economic Review and Outlook (PERO), released on Tuesday, indicated the province accounted for 35.1% of the country's gross domestic product (GDP) in 2010.

Sukazi said the PERO indicated this was expected to increase by 0.4% by 2014.

Metropolitan municipalities contributed the most to the GDP by region for Gauteng.

The City of Johannesburg accounted for about R300-billion, while the City of Tshwane contributed about R176-billion, according to the PERO.

Employment in Gauteng remained a concern, however, with 1.6-million people unemployed and 2.3-million classed as not economically active.

The primary sector – which includes mining and agriculture – employed only 1.5% of Gauteng workers last year.

The secondary (industrial) sector accounted for almost a quarter of jobs in the province.

The largest sector in terms of employment was the service industry, providing three-quarters of Gauteng's jobs.