Johannesburg - Shares of Exxaro drop more than 3 percent as it warns of an impending impairment related to its Mayoko iron ore project in Republic of Congo.

The company says it has been unsuccessful in reaching definitive port and rail agreements for the 12 million tonne project.

Exxaro says the impact of the write-down will be up to 5.4 billion rand.

Exxaro expects headline earnings, which will not include the impact of the impairment, to be in line with the 2.5 billion rand recorded in the first half of 2013.

The company will report on its first six months' performance on August 21.

Exxaro shares are down 3.3 percent at 137.18 rand, compared with a 0.5 percent drop in Johannesburg's All-share index. - Reuters