Israel's help for earthquake-struck Turkey is a purely humanitarian gesture, both countries said on Wednesday, playing down prospects of their troubled relations being on the mend.

Responding to an international appeal by Ankara following Sunday's 7.2 magnitude quake that killed more than 400 people and displaced thousands in the eastern province of Van, Israel planned to fly out a small number of prefabricated homes and said it could ship hundreds more by sea.

We said that we would be prepared to provide all possible aid, as they desire and request, and there is no mixing political-diplomatic relations and natural disasters, Foreign Minister Avigdor Lieberman told Israel's Army Radio.

We are separating the two things absolutely.

Israeli relief after a 1999 Turkish earthquake helped seal an alliance that has since collapsed over Israel's Palestinian policies and its killing last year of nine Turks aboard an activist ship that tried to breach its Gaza blockade.

Despite the crisis, Turkey's Islamist-rooted government sent firefighters to help Israel contain a deadly blaze in its northern Carmel forest in December.

We don't mix humanitarian issues with political issues, a Turkish Foreign Ministry official told Reuters.

We gave the same answer to every country that has offered help. We said we are making an assessment and we will turn to you if there is need for help. We said this to every country, including Israel.

Israel's Defence Ministry said one plane carrying six or seven prefabricated homes was due to depart on Wednesday evening, and another on Thursday. A ship was also being prepared to supply hundreds of the structures, if required.

When a country is in distress and has humanitarian problems, it is right to help and put things aside for a minute, Defence Ministry director-general Ehud Shani told Israel Radio.

Turkey had initially declined Israel's offer of help. Asked whether the turnaround augured reconciliation, Shani was cautious. I think that destruction takes hours. Constructing a building, brick by brick, takes more time, he said.

Therefore every element that we bring to the table will, it seems, bring about some kind of improvement, and we will ultimately reach better days.

Lieberman blamed the breakdown of relations on a dramatic change in Turkish policy but said shifting regional strategies could nudge the countries back together.

He cited more recent Turkish anger at neighbouring Syria's crackdown on a citizen revolt, which has pitted Ankara against two old foes of Israel -- Syria and its ally Iran.

I'm not talking about a warming of relations. I'm talking about trying to identify where the common interests are, Lieberman said.

(Writing by Dan Williams; Editing by Tim Pearce)