AMs have criticised the treatment of a rebel Kurdish leader imprisoned in Turkey.
Abdullah Ocalan is not being held in line with human rights law, a Welsh Assembly motion passed following a Plaid Cymru-led debate said.
Foreign affairs are not devolved, but Welsh minister Eluned Morgan said she had discussed the issue with the Turkish ambassador.
Conservative AM Darren Millar called the motion distasteful.
Abdullah Ocalan, who has been in a high-security prison in Turkey since 1999, leads the Kurdistan Workers' Party (PKK) which is considered a terrorist organisation by the UK government.
Kurds make up the fourth-largest ethnic group in the Middle East, stretching across Turkey, Syria, Iraq, Iran and Armenia, but they have never obtained a permanent nation state.
The debate came about following a hunger strike by Newport's Imam Sis, which began in December last year and was started to protest against Mr Ocalan's treatment.
It follows the hunger strike of Leyla Güven, an elected member of the Turkish Parliament, and others.
Ms Güven has argued that by isolating Mr Ocalan and by refusing to allow visits from his family or lawyers, the government has placed major impediments towards maintaining peace in Turkey.
The PKK, which is based in Turkey and Iraq, has led an armed struggle against the Turkish government on and off for the past 30 years.
The Welsh Assembly motion, tabled by Plaid Cymru, said Mr Ocalan's imprisonment was "under conditions which are understood to contravene the Turkish state's legal obligations in relation to human rights".
It said Mr Sis, along with other hunger strikers, wanted to see a peaceful, political solution to the Kurdish question in Turkey.
It called for the Welsh Government to lobby a Council of Europe committee to assess Mr Ocalan's condition.
Delyth Jewell, the Plaid AM for South Wales East, said: "Surely, it is incumbent on the National Assembly and Welsh Government to recognise and support the part that a Newport man is currently playing in an international struggle for justice, equality and human rights."
Former Plaid Cymru leader Leanne Wood said the hunger strikes aim to pressure the European Committee for the Prevention of Torture to "pay a visit to check on the situation of the Kurdish leader".
She called for the assembly to send a "clear message today that Turkey must cease its barbaric treatment of Kurdish people".
Eluned Morgan, minister for international relations, said her government was "extremely concerned about the worsening condition of Imam Sis from Newport".
She said she raised Mr Sis's hunger strike and the reasons for it with the Turkish ambassador.
She said: "The ambassador asserted that in March 2018 the European Committee for the Prevention of Torture published a report that highlighted that the conditions under which Ocalan had been held had materially improved since their previous visit in 2013.
"It's worth noting however that the European report suggests that the authors had serious concerns about the prisoner's contact with the outside world and this has deteriorated."
She said the matter was not devolved to the Welsh Government, but there was nothing to prevent the assembly writing a letter.
Ministers abstained on the motion but some Labour AMs backed it.
Conservative AM Darren Millar questioned whether the debate was a good use of the assembly's time.
Mr Millar added: "As a person who has visited the Kurdistan region of Iraq just last year, and has Kurdish friends from Turkey and Iraq, I do recognise that there is a desire amongst many Kurdish people for an independent Kurdish state. But regardless of whether people in this Chamber support that aim or not, I would hope that we can all be united in our condemnation of the use of terror to achieve that goal.
The Turkish government says the PKK is "trying to create a separate state in Turkey" the PKK has disputed this.
Winding up Wednesday's debate in Cardiff Bay, Plaid's Delyth Jewell said: "The motion is about human rights and ending the enforced solitary confinement of a political prisoner. And the life of a Welsh citizen— Imam is 32; he's a year older than me, and he might die.
The motion was passed with 25 AMs voting in favour. There were 14 abstentions and 11 voted against.