In October, the Palestinian security forces arrested a man named Issam Akal, a resident of [East] Jerusalem. Akal was suspected of the crime of selling land to Israelis - treason.

Chief Rabbi of Jerusalem Rav Aryeh Stern paskened, in a letter sent to encourage working for Akal's release, that efforts to resolve Akal's situation and get him released fall under the category of the mitzva of pidyon shvuyim - redeeming captives, which is a tremendous mitzva.

Rav Stern referenced the Gemara that says we support poor gentiles along with poor Jews, so the same will also apply for redeeming gentile captives just as we redeem Jewish captives. Rav Stern said anyone working for his release would also have a mitzva of yishuv haaretz - settling of the land, as others will see that the Jews work to protect them and will also be encouraged and willing to sell land to jews.
source: Israel Hayom and Kikar