Telstra has reported increased net profit by 8.8 per cent to $1.6 billion for the half year ending December 31.

Telstra CEO, David Thodey, said the telco invested $1.9 billion in capital expenditure during the six months, which includes its national mobile network. It has sold about 1.5 million 4G devices and he said it was on track to expand 4G coverage to 66 per cent by June.

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"We continue to see customer growth in key products and services, particularly mobiles," Thodey said.

The telco added 607,000 new domestic mobile customers in the six months to December, bringing the number to 14.4 million.

It also announced a 14 cent fully franked interim dividend representing a $1.7 billion return to shareholders.

More to follow.