German Chancellor Angela Merkel warned on Tuesday that Britain should not expect to retain privileges it had before without fulfilling certain obligations in negotiations over its new relations with the European Union.

"We will make sure negotiations are not guided by the principle of 'cherry-picking,'" Merkel told the lower house of German parliament before heading to Brussels for a summit with European leaders.

"There must be a noticeable difference whether a country wants to be a member of the EU or not," she said, "Whoever wants to leave this family cannot expect to lose all the obligations while keeping the privileges."

Merkel added that Britain, which opted to leave the EU in a referendum last week, would not get access to the European single market without accepting obligations such as freedom of movement, mentioning Norway which accepted free migration from the EU in return for access to the internal market.

"This applies to Britain as it does to everyone else," she said.

The German leader reiterated that no formal or informal negotiations over Britain's future relations with the EU would start until the country formally notifies its intention to leave.

As long as Britain hasn't formally exited the bloc, it remains an EU member state and "all rights and obligations of membership would continue to apply to both sides."

Merkel expressed confidence that the EU is "strong enough" to withstand a withdrawal of Britain.

"Any suggestions that could lift the EU out of this crisis are welcome," she said, adding that she and the German government would make every effort to prevent nationalist forces in the EU from strengthening.