UPDATE 3-European contracts, high costs sour Gazprom outlook

* Q2 opex up 13.5 percent, debt up 31 percent in H1

* Net profit 192.6 billion roubles, vs forecast 188.15 bln

* "Take or pay" penalties could amount to $2.5 billion

* Gazprom (GAZP.MM) shares end up 3.9 pct, lagging market

(Adds conference call, updates share price)

By John Bowker and Katya Golubkova

MOSCOW, Nov 9 (Reuters) - Gazprom, the world's biggest gas company, raised the spectre of a row with European customers not buying all the gas contracted for in 2009, while rising costs and debt took the shine off its quarterly profits.

Russia's monopoly gas exporter said costs rose 13.5 percent in the three months to end June, partly due to more expensive gas from central Asia, while debt soared 31 percent in the first half to 1.34 trillion roubles ($46 billion).

"We are disappointed by the company's inability to control opex (operating expenditure) in the current environment. We feel that rising competition from low-cost producers, both in Europe and Russia, will put further pressure on the company's profitability," said Citi analysts in a note.

Even so, the second-quarter net profit beat analysts' forecasts as demand for gas picked up from the trough of the global economic crisis.

Gazprom shares closed up 3.93 percent in Moscow, but the wider Moscow index was up 5.05 percent.

Gazprom said in a statement on Monday that second-quarter profit attributable to shareholders was 192.6 billion roubles ($6.6 billion), a big drop on the same period a year ago but up from the 110 billion roubles made in the three months to end-March.

TROUGH

Analysts polled by Reuters had on average forecast a profit of 188.15 billion roubles for the period.

They said after publication of the results that the year-on-year decline had been expected due to the economic downturn and that winter could be crucial for the company.