Africa's largest steel producer Mittal Steel South Africa would increase certain steel prices both in June and in July, Mittal Steel South Africa spokesperson Tami Didiza said.

On Thursday, galvanised steel prices increased by 9% and colour coasted steel by 6%.

On July 1, galvanised steel prices would increase by 15% and colour coasted steel by 8%, Didiza said.

Also on July 1, hot rolled coil prices would increase by 5%, cold rolled would increase by 4% and plate by 12%, he added.

On a weighted average basis, steel prices will increase by 5% in July with about 85% of flat product steel prices to be hiked.

One of the key reasons for the increase was the increase in zinc prices, which had tripled over the past few months, Didiza said.

"We should have effected the increase a long time ago," he added.

Certain long product steel prices that used nickel and molybdenum prices would increase by 5%, Didiza stated.

Mittal Steel South Africa's Chief Executive Officer Davinder Chugh on Thursday was reluctant to comment on the next move in local steel prices, despite the 20% increase in global steel prices since the beginning of the year.

The company has not increased domestic steel prices since October 2004 and reduced the local steel price twice in 2005.

Internationally, the major steel mills in Europe and the US have increased their third quarter steel prices and most other steel markets are reflecting an upward trend, Chugh said.