UPDATE 1-Thai PTTEP may miss 2010 sales target due to Montara

* Montara field start-up delayed again to Q2/2010 from Q1

* Upbeat on 2010 performance due to new output

* Shares pare gain after rising 1.3 pct (Adds details)

BANGKOK, Oct 26 (Reuters) - Thailand's PTT Exploration and Production PTTE.BK (PTTEP) said on Monday it was likely to miss its 2010 petroleum sales target of 300,000 barrels per day due to a delay in the start-up of its Montara oil field in Australia.

The Montara field, which has had an oil spill problem since late August, was now expected to start operations in the second quarter of next year, delayed from the first quarter, Chief Executive Anon Sirisaengtaksin told reporters.

"We have a target of 300,000 bpd for next year, but I think it should be below that because the start-up of Montara will be delayed by another quarter," Anon said.

Analysts expect sales volume of 290,000-291,000 bpd in 2010.

Before the spill, Montara had been expected to start producing in the fourth quarter of this year.

PTTEP, a subsidiary of top energy firm PTT (PTT.BK), had planned to produce about 35,000 bpd from the Montara field, which would have boosted its 2009 petroleum sales to 240,000 bpd.

Last week, Anon said 2009 sales should be below target by 3-5 percent.

The Montara field could be one of the main sources of profit for PTTEP in future. Many analysts expect higher output from new oil and gas fields to boost sales.

PTTEP owns 100 percent of the Montara field through its wholly owned Australasia, formerly known as Coogee Resources, which the Thai firm acquired this year.

It is the flagship in the exploration and production business of the PTT group and is involved in about 40 oil and gas exploration and development projects in 14 countries in the Middle East, Africa and Asia.

Anon said he was upbeat about the company's financial performance for next year thanks to new output from the Montara field and a Malaysian-Thai joint development area.

On Monday, PTTEP shares closed down 0.32 percent, after rising 1.3 percent earlier, while the overall market was 0.43 percent higher. ($1 = 33.41 Baht) (Reporting by Manunphattr Dhanananphorn; Writing by Khettiya Jittapong; Editing by Alan Raybould)