Germany’s parliament is expected to vote to legalise same-sex marriage despite divisions on the issue inside Angela Merkel’s party.

The opposition Social Democratic Party (SPD) called for the vote in an amendment entitled “marriage for all”, in a key victory ahead of September’s federal elections.

“We will push through marriage equality in Germany. This week,” said Martin Schulz, the SPD head and former European Parliament president.

At a parliamentary group meeting on Wednesday, Ms Merkel accused his party of “ambushing” her by bringing forward a vote on an issue that divides her conservative Christian Democratic Union (CDU).

“It's sad and completely unnecessary that such a decision has turned into a political confrontation at the very moment when there was a realistic outlook for a process that could have crossed party lines,” the Chancellor told Wirtschaftswoche magazine. “Every member of parliament should be able to follow their conscience.”

Ms Merkel’s party, which holds 254 out of 630 seats in the Bundestag lower house of parliament, is currently governing in coalition with the SDP, whose members hold high-profile posts including the foreign and economy ministers.

LGBT+ rights around the globe Show all 9 1 /9 LGBT+ rights around the globe LGBT+ rights around the globe Russia Russia’s antipathy towards homosexuality has been well established following the efforts of human rights campaigners. However, while it is legal to be homosexual, LGBT couples are offered no protections from discrimination. They are also actively discriminated against by a 2013 law criminalising LGBT “propaganda” allowing the arrest of numerous Russian LGBT activists. AFP/Getty LGBT+ rights around the globe Brunei Brunei recently introduced a law to make sodomy punishable by stoning to death. It was already illegal and punishable by up to 10 years in prison AFP/Getty LGBT+ rights around the globe Mauritania Men who are found having sex with other men face stoning, while lesbians can be imprisoned, under Sharia law. However, the state has reportedly not executed anyone for this ‘crime’ since 1987 Alamy LGBT+ rights around the globe Sudan Both male and female same-sex sexual activity is illegal under Sudanese law. Men can be executed on their third offence, women on their fourth Getty LGBT+ rights around the globe Saudi Arabia Homosexuality and gender realignment is illegal and punishable by death, imprisonment, whipping and chemical castration Getty LGBT+ rights around the globe Yemen The official position within the country is that there are no gays. LGBT inviduals, if discovered by the government, are likely to face intense pressure. Punishments range from flogging to the death penalty Getty LGBT+ rights around the globe Nigeria Both male and female same-sex sexual activity is illegal and in some northern states punishable with death by stoning. This is not a policy enacted across the entire country, although there is a prevalent anti-LGBT agenda pushed by the government. In 2007 a Pew survey established that 97% of the population felt that homosexuality should not be accepted. It is punishable by 14 years in prison Reuters LGBT+ rights around the globe Somalia Homosexuality was established as a crime in 1888 and under new Somali Penal Code established in 1973 homosexual sex can be punishable by three years in prison. A person can be put to death for being a homosexual Reuters LGBT+ rights around the globe Iraq Although same-sex relationships have been decriminalised, much of the population still suffer from intense discrimination. Additionally, in some of the country over-run by the extremist organisation Isis, LGBT individuals can face death by stoning Getty

The party took the Chancellor’s statement on a “vote of conscience” to free it from its obligation not to call a vote on same-sex marriage.

German politicians are expected to vote in favour in the Bundestag today after Ms Merkel announced that CDU/CSU members would be free of the party whip.

Equal marriage is a key issue for the centre-left party, and smaller opposition parties the Left (Die Linke) and the Greens, meaning supporters have a slim majority in the Bundestag.

The Netherlands was the first European country to legalise same-sex marriage, back in 2001, followed by countries including Belgium, Spain, Canada, Norway, Sweden, Portugal, Iceland, Denmark, France and the UK.

With almost of its neighbours supporting legal unions between gay partners, calls have been increasing in Germany for the government to drop resistance that appears increasingly anachronistic.

But Ms Merkel's apparent U-turn generated anger among her own politicians, who have been arguing the CDU/CSU’s 14-point poll lead over the SPD mean it should not to defer to the party.

Arlene Foster on gay marriage: "I believe in union between a man and a woman"

“Are we going to change our view whenever it is politically convenient?” asked lawyer and politician Wolfgang Bosbach in the Stuttgarter Zeitung.

The proposal for same-sex marriage, first moved in 2015 in the upper house of parliament by the state of Rhineland Palatinate, could be signed into law by the President after 7 July.

It comes amid concerns over a rise in documented right-wing extremism in Germany.

Interior ministry figures show that 462 right-wing offenders are on the run under arrest warrants for offences including violence and “politically motivated” crimes.

Die Linke, which requested the figures, said the refugee crisis had sparked an increasing risk of Islamist terrorism in Germany, but also a “real, but less-recognised peak” in far-right violence.

Counter-terror police uncovered paramilitary training camps for far-right extremists armed with guns and weapons last week, while an anti-government Reichsbürger murdered a German police officer last year and several far-right bombing plots have been foiled.

Nationalist and neo-Nazi groups have been attempting to capitalise on fears over the refugee crisis and three Isis-linked terror attacks launched by asylum seekers in Germany.