By Noah Browning

LONDON, Feb 23 (Reuters) - Emissions of the potent greenhouse gas methane coming from the global energy sector are 70% higher than officially reported, the International Energy Agency (IEA) said on Wednesday, with the coal sector identified as the biggest single source.

In its 2022 Global Methane Tracker report, the Paris-based watchdog said the world needed to step up its monitoring efforts and policy action to curtail emissions of the polluting gas.

Contributions from the coal industry to the problem had been logged for the first time, topping the other major parts of the fossil fuel sector at 42 million tonnes (Mt), followed by 41 Mt and 39 Mt from oil and natural gas respectively.

The report provides the first ever comprehensive emissions estimates for each country, in which some possible signs of progress reining in the problem were seen.

"Methane emissions from the energy sector grew by just under 5% last year," the IEA said. "This did not bring them back to their 2019 levels and slightly lagged the rise in overall energy use, indicating that some efforts to limit emissions may already be paying off."

More than 100 countries joined a U.S.- and EU-led effort to cut emissions of methane 30% by 2030 from 2020 levels at the COP25 climate conference in Glasgow, Scotland, last year.

Methane is the main greenhouse gas after carbon dioxide. It has a higher heat-trapping potential than CO2 but breaks down in the atmosphere faster - meaning that cutting methane emissions can have a rapid impact on reining in global warming.

The energy sector accounts for around 40% of methane emissions from human activity, the IEA said. Other industries, with agriculture at the top, are also big methane emitters.

"Methane leaks multiply the climate impact of burning coal. This issue can no longer be ignored," said Anatoli Smirnov, coal mine methane lead at London-based climate research group Ember.

"To date, coal companies have done very little to reduce methane leaks, despite the existence of cost-effective technologies," he added in a statement.

Fatih Birol, the IEA's executive director, lamented the prospect that had all methane leaks from the fossil fuel industry been captured and sold last year, the world could have been furnished with 180 billion cubic metres of natural gas.

"At today's elevated gas prices, nearly all of the emissions from oil and gas operations worldwide could be avoided at no net cost," he was quoted as saying.

The IEA estimated that the lost methane was equivalent to all the gas used in Europe's power sector and more than sufficient to ease the tight supply which have driven up prices.

(Reporting by Noah Browning; Editing by Sandra Maler)