Several German lawmakers said on Sunday the country's soldiers working at Turkey's Incirlik airbase should be brought home if Ankara continued to prevent parliamentarians from visiting the station.
Turkey, angered by a resolution passed by the German parliament last month that branded the 1915 massacre of Armenians by Ottoman forces a genocide, has denied German lawmakers access to the base.
Some 250 German soldiers are taking part in NATO operations at Incirlik against Islamic State militants in Iraq.
Relations between Germany and Turkey - crucial partners in the effort to stem mass migration to Europe - have been strained ever since the Armenian resolution, which prompted Ankara to recall its ambassador.
A leader of Germany's opposition Greens, Cem Ozdemir, who is of ethnic Turkish origin, told ARD television the situation was unacceptable.
"As lawmakers who send soldiers to places, we must know where they are, how they are and be able to talk to the soldiers. If that is not possible in Turkey then the soldiers must come back to Germany," he said.
Lawmakers approve military spending and investment in infrastructure at the base.
Parliamentarians from other parties, including the centre-left Social Democrats (SPD), joined the plea to Chancellor Angela Merkel to get Turkey to agree to allow access.
Merkel met Turkish President Tayyip Erdogan on the sidelines of a NATO summit in Warsaw on Saturday and described the atmosphere as constructive but said their underlying differences remained.
Andreas Scheuer, General Secretary of the Bavarian Christian Social Union (CSU) who are part of Merkel's conservative bloc in parliament, said lawmakers had to be allowed to visit soldiers.
"As a result of his behaviour, Turkish President Erdogan is risking the withdrawal of the German army," he told Monday's Tagesspiegel daily, according to extracts sent in advance.
Turkey accepts that many Christian Armenians living in the Ottoman Empire were killed in clashes with Ottoman forces during World War One but it denies that up to 1.5 million were killed and that the killings constitute a genocide. It also says many Muslim Turks died in the clashes.