A same-sex partner may be entitled to a survivor's work pension where gay couples have partnership rights similar to marriage, the European Union's top court said on Tuesday.

It will still be up to the domestic courts in EU member states to decide if any national laws on registered gay partnerships put such relationships on par with marriage for the ruling to have effect.

The ruling follows a German court case and is binding in all the EU's 27 member states.

"A life partner of the same sex may be entitled to a survivor's pension under an occupational pension scheme," the European Court of Justice said in a statement.

"The national court must determine whether a surviving life partner is in a situation comparable to that of a spouse who is entitled to the survivor's pension at issue," the court said.

The original case involved Tadao Maruko, who entered into a registered life partnership with a designer of theatrical costumes in Germany. Maruko's partner, who died in 2005, had been a member of the Versorgungsanstalt der deutschen Buehnen, which managed pensions for people working in the German theatre. After his partner's death, Maruko applied for a widower's pension but was rejected and a German court referred the case to the EU court in Luxembourg. The top court said EU rules to stop discrimination -- such as on the grounds of sexual orientation -- in employment and occupation were applicable.

Although Germany reserved marriage solely to persons of different sex, it has established that life partnerships have been gradually made equivalent to marriage, the court said. "Consequently, the court rules that the refusal to grant the survivor's pension to life partners constitutes direct discrimination on grounds of sexual orientation, if surviving spouses and surviving life partners are in a comparable situation as regards that pension," the court said.

The EU executive European Commission welcomed the ruling. "It's not the Commission or any other European institution that imposes on Germany or any other member state whether or not marriage or registered couples must be treated equally," a Commission spokeswoman said. In EU countries with no gay partnership laws the ruling by the court would not apply, the Commission said. "It's a national competence, not a community competence, in deciding about family law, the law of partnerships and marriage," the Commission said.