International Federation of Journalists head Aidan White is to visit Gaza to deliver a letter calling for the release of BBC reporter Alan Johnston.
Alan Johnston has reported from Gaza for three years
About 200 members of the European parliament have signed the letter.
It calls on the Palestinian Authority and the EU to make every effort to secure the freedom of Mr Johnston, who has been missing for more than a month.
A jailed leader of Palestinian faction Fatah, Marwan Barghouti, on Wednesday also demanded that he be freed.
The MEPs are calling on the EU, and in particular the major donor countries, to take strong action in helping to secure Alan Johnston's release.
While the EU suspended direct aid to the Palestinian Authority following the election of Hamas, it remains a major source of finance to specific aid programmes.
Earlier this week, senior EU officials addressed a rally in support of Mr Johnston outside the European Commission headquarters in Brussels.
No further news
The BBC says it has had no confirmation of a statement by a previously unknown Palestinian group that it had killed Alan Johnston.
On Wednesday, Mr Barghouti called Mr Johnston a "friend of the Palestinian people" in a statement from prison in Israel.
Barghouti is one of the most prominent Palestinians held in Israel. He is serving five life sentences for attacks which killed four Israelis and a Greek monk.
Mr Johnston was kidnapped by masked gunmen after he left his Gaza office on 12 March and has not been heard from since.