HELSINKI, Aug 2 (Reuters) -Finnish forest industry group UPM-Kymmene does not expect any significant improvement in its low mill operating rates in the third quarter, the group's Chief Executive said on Thursday. ``Our operating rates will remain low, and we will try to avoid inventory build-up,'' Chief Executive Juha Niemela told a news conference. ``We can hardly improve our presently low operating rates in the third quarter,'' he added. Niemela noted that producers' stocks of pulp had remained high and users' inventories low, which would continue to keep pulp prices under presure. ``We have hardly yet see the rock-bottom (in pulp prices) at this level,'' he said. Niemela said that the four mills that UPM is acquiring from German paper producer Haindl had performed well and that profitability there remained very good, and according to expectations, but operating rates there had also declined. Asked if Haindl remained one of the most profitable groups in the industry, Niemela said: ``No doubt.'' The company expects official clearance of the acquisition in November, he repeated.