INTERVIEW-UPDATE 1-Thai PTT weighs $1.2 bln bonds to refinance

* Mulls 40 bln bond issues to refinance debt

* PTT, PTTEP to invest $20 bln in next 5-6 yrs

* Expects weak performance in H2

(Adds details)

By Khettiya Jittapong and Wilawan Pongpitak

BANGKOK, July 14 (Reuters) - PTT PCL PTT.BK, Thailand's top energy firm, is considering selling up to 40 billion baht ($1.2 billion) worth of bonds later this year, mostly in foreign markets, to refinance its debt.

A bond sale would allow Thailand's largest listed firm to minimise risks in the face of volatile markets, rising interest rates and inflation, PTT's chief financial officer Pichai Chunhavajira told Reuters in an interview.

"What I have to do is to make sure we have enough liquidity to finance our expansion. We have to refinance our debt to be longer term and in line with our investment plans," he said. The bonds would be issued in several tranches, he said, adding that other details would depend on market conditions. PTT's debt now stands at 187 billion baht, by far the largest share of the 215 billion baht in debt held by the PTT group of companies. Some 73 percent is denominated in Thai baht, 24 percent in dollars and the remaining 3 percent in yen.

The average financing cost of the group debt is about 5.5 percent, according to company data.