The United Nations said Friday that groups seeking to deliver aid to Gaza should do so by land, after Israel warned it would intercept two ships seeking to break a blockade of the Palestinian enclave. “There are established routes for supplies to enter by land. That is the way aid should be delivered to the people of Gaza,” UN spokesman Martin Nesirky told a press briefing. “Our stated preference has been and remains that aid should be delivered by established routes, particularly at a sensitive time in indirect proximity (peace) talks between Palestinians and Israelis,” he added. He made the comments after Israel served notice its forces would prevent a planned Lebanese aid flotilla from reaching the Gaza Strip. “We have received information in recent days about a plan to send a new flotilla to break the blockade around Gaza,” Israeli Defense Minister Ehud Barak said on Israeli television.