* Euro zone worries move again to forefront
* Indexes off: Dow, S&P, Nasdaq all 0.3 pct
* For up-to-the-minute market news, see (Updates to early trading)
By Chuck Mikolajczak
NEW YORK, Feb 6 (Reuters) - U.S. stock fell on Monday after a five-week rally on concerns Greece may be unable to avoid a chaotic default as it struggles to reach terms on a new bailout package.
Athens allowed another deadline to slip as political leaders failed to respond to terms for a new bailout from the European Union and Internation Monetary Fund. Greece needs the funds by March to meet big debt repayments.
German Chancellor Angela Merkel stepped up pressure on Greece, warning that time was running short for a deal to be struck.
"It’s inevitable the risk profile that Greece represents is definitely going to cool the market tone, there is absolutely no way around that," said Peter Kenny, managing director at Knight Capital in Jersey City, New Jersey.
"That lack of clarity, the protracted nature of this crisis and the fact that it simply will not go away, it’s a bit unnerving to people who have seen the market tack on some very nice early year gains, and it forces people to want to be a little cautious."
The Dow Jones industrial average was down 39.01 points, or 0.30 percent, at 12,823.22. The Standard & Poor’s 500 Index was down 3.86 points, or 0.29 percent, at 1,341.04. The Nasdaq Composite Index was down 7.66 points, or 0.26 percent, at 2,898.00.
Read more at Reuters