* Net profit at 106 million euros, beats forecasts
* Adjusted profit advances 4 percent to 63 million euros * Upgrades of refineries are on time, budget (Adds details)
ATHENS, Aug 27 (Reuters) - Greece's biggest refiner, Hellenic Petroleum said on Thursday second-quarter net profit dropped because it posted fewer gains on the value of its inventories and took provisions for an early retirement plan.
Net earnings declined 18 percent year-on-year to 106 million euros ($150.9 million), slightly exceeding market expectations. Analysts polled by Reuters were expecting net profit of 104.1 million euros.
But stripping out the effect of lower oil prices on the value of oil inventories and other non-operating items, adjusted "clean" net income was 63 million euros compared with 60 million euros last year, above analysts' estimate of 51.6 million.
"These results, combined with a strong balance sheet demonstrate our ability to weather the challenging times," Hellenic Chief Executive Officer John Costopoulos said in a statement.
The results include a 39 million euro provision for a plan to send more than 150 workers into early retirement. Upgrades of the company's Elefsina and Thessaloniki refineries were progressing on time and within budget, the company said.
Hellenic is active in 10 countries in southeast Europe, from oil exploration and refining to petrol stations and petrochemicals. In June, the company announced the acquisition of the Greek gas station network of BP Plc for 359 million euros.
The stock trades at about 14 times estimated 2009 earnings, which compares with a multiple of about 12 for shares in rival Motor Oil. (Reporting by Harry Papachristou; Editing by Jon Loades-Carter and Rupert Winchester)