Under the Paris Agreement on Climate Change, brokered in 2015, nations have to submit revised plans to reduce emissions, known as nationally determined contributions, every five years.

Norway said on Friday it was one of the first countries to submit enhanced reduction plans to the United Nations and would increase its ambition to a cut of at least 50% from 1990 levels by 2030, up from a previous pledge of a 40% cut.

"Norway's new and strengthened target is to reduce emissions by at least 50%, and towards 55% by 2030 compared to 1990 levels," the ministry of climate and environment said in a statement.

So far Norway's emissions are close to flat, according to the latest available data. In 2018 they were 1% higher versus 1990 levels. Oil and gas contributes more than a quarter of Norway's total emissions of 52 million tonnes of carbon.

Non-EU member Norway said it wished to fulfil the enhanced target in collaboration with another non-EU nation Iceland and with the European Union, which has promised new laws in March to make the bloc climate neutral by 2050.

Current rules allow Norway to pay for emissions reductions elsewhere in the EU in order to prevent it producing above agreed limits, but it is seeking to achieve most of its emission cuts at home.

Already it has the world's highest rate of electric car use and has embarked on efforts to bury emissions.

Its state-controlled oil and gas firm Equinor pledged in January to cut greenhouse emissions from its domestic operations by 40% this decade and to near zero by 2050.

Pressure is mounting on countries and companies that rely on fossil fuel as investors are increasingly unwilling to finance projects that ignore the need to slow global warming.

But climate campaigners are concerned that the momentum that brought about the Paris climate deal in 2015 has ebbed away as the steps now needed to prevent temperatures rising are likely to be expensive and disruptive.

They say the next international climate conference in Glasgow in November will be a crucial test of whether the United Nations' global approach can work after talks in Madrid in December ended in compromise.

By Nerijus Adomaitis