Israel stripped more than 100,000 residents of Gaza and some 140,000 residents of the West Bank of their residency rights during the 27 years between its conquest of the territories in 1967 and the establishment of the Palestinian Authority in 1994.

As a result, close to 250,000 Palestinians who left the territories were barred from ever returning.

Given that Gaza's population has a natural growth rate of 3.3 percent a year, its population today would be more than 10 percent higher, had Israel not followed a policy of revoking residency rights from anyone who left the area for an extended period of time. The West Bank's population growth rate is 3 percent. Many of those prevented from returning were students or young professionals, working aboard to support their families.

The data on Gaza residency rights was released by the Defense Ministry's Coordinator of Government Activities in the Territories this week, in response to a freedom-of-information request filed by Hamoked - The Center for the Defense of the Individual. In its letter, COGAT said that 44,730 Gazans lost their residency rights because they were absent from the territory for seven years or more; 54,730 because they did not respond to the 1981 census; and 7,249 because they didn't respond to the 1988 census.

It added that 15,000 of those deprived of residency are now aged 90 or older.

In May 2011, Haaretz obtained the figures on West Bank residents who were stripped of their residency rights. The report noted that Israel had, for years, employed a secret procedure to do so. Palestinians who went abroad were required to leave their identity card at the border crossing. Unlike those from Gaza, who were allowed to leave for seven years, these Palestinians received a special permit valid for three years. The permit could be renewed three times, each time for one year. But any Palestinian who failed to return within six months after his permit expired would be stripped of his residency with no prior notice.

Former senior defense officials told Haaretz at the time of that report's publication that they were unaware of any such procedure.

Today, a similar procedure is applied to East Jerusalem residents: A Palestinian who lives abroad for seven years or more loses his right to return to the city.

GOGAT's letter to Hamoked regarding the Gaza natives said that there are various ways for Palestinians to get their residency restored, and in fact, some of those Gazans who lost their residency rights later regained them. However, it added, it lacks the resources to comply with Hamoked's request to be told the specific reason behind each such restoration.

Since many of those who lost their residency rights from 1967 to 1994 in both Gaza and the West Bank were students or young professionals, their descendants today presumably number in the hundreds of thousands. Of the original people affected by the policy - nearly 250,000 - many have since died. But several thousands who were affiliated with the PA were granted the right to return in 1994; still other Palestinians have since been allowed to return for a variety of reasons.

Among the more prominent West Bank residents who have been barred from returning are the brothers of the PA's chief negotiator, Saeb Erekat, who went abroad to study and subsequently lost their residency. They now live in California. Erekat said that having learned from their experience, he was careful to return to the West Bank periodically while he was studying abroad, so as to keep his residency permit valid.

Hamoked, which learned of the existence of this policy by chance while investigating the case of a West Bank resident jailed in Israel, charges that stripping tens of thousands of Palestinians of their residency - and thus effectively exiling them permanently from their homeland - is a grave violation of international law.