JERUSALEM — Israel laid claim on Sunday to nearly 1,000 acres of West Bank land in a Jewish settlement bloc near Bethlehem — a step that could herald significant Israeli construction in the area — defying Palestinian demands for a halt in settlement expansion.

Peace Now, an Israeli group that opposes the construction of settlements in the West Bank, said that the action on Sunday might be the largest single appropriation of West Bank land in decades and that it could “dramatically change the reality” in the area.

Palestinians aspire to form a state in the lands that Israel conquered in 1967.

Israeli officials said the political directive to expedite a survey of the status of the land came after three Israeli teenagers were kidnapped and killed in June while hitchhiking in that area. In July, the Israeli authorities arrested a Palestinian who was accused of being the prime mover in the kidnapping and killing of the teenagers. The timing of the land appropriation suggested that it was meant as a kind of compensation for the settlers and punishment for the Palestinians.