Perth transport company CTI Logistics has announced another first-half profit upgrade, its second in two months.

The company said it now expected profit before tax in the six months to the end of December to be up by 60-62 per cent on the previous corresponding period.

Today's announcement follows a statement on November 29 last year that profit before tax would be up 33-44 per cent on the previous corresponding period.

CTI posted a first-half net profit of $3.9 million and profit before tax of $5.5 million for the six months to the end of December 2011.

The upgrade would give the company a pre-tax profit of $8.8-9.1 million profit for the six months to the end of December 2012.

CTI attributed the improved performance to an increase in revenue and profit largely related to the resources sector.