Updated 4.40pm 

Angela Merkel told top members of her party today that she wants to run for a fourth term as German chancellor in next year's election, senior party sources said, after months of speculation about one of the world's most powerful women.

Despite a voter backlash over her open-door migrant policy, the conservative is seen as a stabilising force in Europe amid uncertainty caused by Britain's vote to leave the European Union and the election of Donald Trump as the next US president.

Merkel told leading figures in her Christian Democrat (CDU) party about her intentions at a meeting to prepare for the September election, several participants said.

Colleagues welcomed the long-awaited decision, which she is expected to announce at a news conference at 1800 GMT.

"Angela Merkel stands for stability, reliability and thoughtfulness," said senior CDU politician Julia Kloeckner.

"With her straightforward and calm nature she had led us safely through the financial and economic crises," she told the Rheinische Post newspaper.

Some 55 per cent of Germans want Merkel, Germany's eighth chancellor since World War Two, to serve a fourth term, with 39 per cent against, an Emnid poll showed on Sunday, highlighting that despite setbacks, she is still an electoral asset.

Merkel, 62, has steered Europe's biggest economy through the euro zone debt crisis and has won respect internationally, for example with her efforts to help solve the Ukraine crisis. US President Barack Obama last week described her as an "outstanding" ally.

Some 55 per cent of German voters want Merkel to run. Photo: Reuters

With Trump's victory in the United States and the rise in support for right-wing parties in Europe, some commentators see Merkel as a bastion of Western liberal values.

However, her decision last year to open Germany's borders to around 900,000 migrants, mostly from war zones in the Middle East, angered many voters at home and dented her ratings.

Her party has slumped in regional elections in the last year while support for the anti-immigrant Alternative for Germany (AfD) has swelled.

Humbled

In September, after a heavy defeat for the CDU in a Berlin state election, a humbled Merkel surprised the country by saying she wished she could turn the clock back on the migrant crisis, though she stopped short of saying her policy was a mistake.

An Emnid poll on Sunday put Merkel's conservative bloc down one point at 33 percent, nine points ahead of her nearest rivals, the Social Democrats (SPD), with whom she shares power.

In a system where coalition governments are the norm, many pollsters see another 'grand coalition' as the most likely option after the election, although the rise of the AfD makes coalition arithmetic more complicated.

The SPD has not decided whether its chairman Sigmar Gabriel, Vice Chancellor and Economy Minister, will run against Merkel.

One of the SPD's deputy leaders, Ralf Stegner, said it would be a mistake to underestimate Merkel but that the "myth of invincibility" was over.

Merkel, who grew up in Communist East Germany, is a physicist who only became involved in politics after the fall of the Berlin Wall in 1989. She is seen as a talented negotiator but has also shown a ruthless streak.

A Protestant woman in a mainly Catholic and male-dominated party, at least when she became its leader in 2000, Merkel never built up a regional power base but over the years she has sidelined her main male rivals and has no obvious successor.

She still requires the backing of her Christian Social Union (CSU) allies in Bavaria, who have fiercely criticised her open-door migrant policy but, with no obvious candidate of their own, are widely expected to fall in behind her.

Germany has no limit on the number of terms a chancellor can serve. By standing again, Merkel could end up matching the 16 years in office of her former mentor, Helmut Kohl. It was Merkel herself who broke with Kohl and told her party in 1999, in the midst of a funding scandal, that it should move on without him.

If she wins a fourth term, it is unclear whether she would serve a full four years. She has said in the past she wants to find the right time to leave politics, and not stay too long.