The key gauge of the current state of the economy topped the boom-or-bust line of 50 percent in March for the first time since December 2000, the government said Thursday in a preliminary report.

The coincident index rose to 56.3 percent, up from a revised 40 percent in February, the Cabinet Office said. A reading below 50 percent is considered a sign of economic contraction and a figure above is viewed as a sign of expansion.

"The coincident index surpassing 50 percent for the first time in 15 months can be interpreted that the Japanese economy is gradually emerging from a severe situation," said Yoshihiko Senoo, director of the Business Statistics Department at the Cabinet Office's Economic and Social Research Institute.