The German government has raised the emergency level for natural gas supplies to the second "alarm" stage of its three-level plan as flows from Russia sharply drop.

The government declared the phase on Thursday, and said that if Russian supplies remain low, Germany may not be able to store enough gas to meet surging demand for heating in winter.

The government is now urging people and companies to increase their efforts to cut back on gas use.

It is also calling on utilities to prepare to resume the operation of currently offline coal-fired thermal power plants to help reduce gas consumption in electricity generation.

Gas flows from Russia via the Nord Stream 1 pipeline have plunged by about 60 percent since Russian gas giant Gazprom announced a steep drop in supplies last week.

German Federal Minister for Economic Affairs and Climate Action Robert Habeck sought the public's understanding of the government's move.

He told reporters that the reduction in gas supplies is an economic attack on Germany by Russian President Vladimir Putin.

Germany had maintained the first phase of its emergency plan since March, saying the prospects for gas supplies were uncertain. The first phase involves stricter monitoring of supplies.