(Adds details, analyst comments)

* Bank of Thailand holds key rate at record low 0.50%

* 2020 GDP forecast raised to -6.6% vs -7.8% seen earlier

* 2021 GDP outlook cut to +3.2% vs +3.6% earlier

* Says new outbreak to have some impact, should be controlled

BANGKOK, Dec 23 (Reuters) - Thailand's central bank left its key interest rate unchanged at a record low on Wednesday but downgraded its 2021 economic outlook as the tourism-reliant country deals with a fresh outbreak of coronavirus.

Southeast Asia's second-largest economy continues to recover, but downside risks remains high and it needs the low policy rate, the Bank of Thailand aid.

The BOT's monetary policy committee voted unanimously to keep the one-day repurchase rate unchanged at a record low of 0.50% for a fifth straight meeting, after three cuts earlier this year.

"The committee voted to maintain the policy rate at this meeting to preserve the limited policy space in order to act at the appropriate and most effective timing," the BOT said.

All but one of 13 economists in a Reuters poll had expected the BOT to remain on hold after three rate reductions earlier in the year. One analyst foresaw a 25-basis-point cut.

With debt holiday over and asset quality concerns, the BOT might cut the rate in the next quarter, said Kobsidthi Silpachai, head of capital markets research of Kasikornbank.

"While there is light at the end of the tunnel, we remain inside the tunnel," he said.

Raising its 2020 economic outlook to a 6.6% contraction from the 7.8% decline, the BOT cut its 2021 outlook to 3.2% growth from 3.6% seen earlier due to sluggish tourism.

It now expects 5.5 million foreign tourists next year, rather than 9 million projected previously. That compares with nearly 40 million visitors in 2019.

The coronavirus spread in a province near the capital Bangkok that has already infected more than 1,000 people since it began at the weekend, in a further blow to the economy still reeling from the global impact of COVID-19.

The spread has added problems for a country already grappling with prolonged political protests, the strength of the baht and below-target inflation.

The BOT reiterated its concerns over the baht's strength and should it would consider measures as necessary.

But the epidemic should be controlled and have only some economic impact, MPC secretary Titanun Mallikamas told a briefing.

(Reporting by Orathai Sriring, Kitiphong Thaichareon and Satawasin Staporncharnchai; editing by Sam Holmes, Larry King)