U.S. regulators extended a ban on domestic carriers’ flights to Israel’s busiest airport for as long as 24 more hours, citing the hazard from rockets fired by Palestinian militants.The Federal Aviation Administration is “working closely with the government of Israel to review the significant new information they have provided and determine whether potential risks to U.S. civil aviation are mitigated,” according to a statement from the agency today. The decision maintains the no-fly rule imposed Tuesday after a rocket fired from the Gaza Strip landed about a mile from Ben Gurion International Airport near Tel Aviv. Israeli officials urged the U.S. to allow service to resume, and El Al Israel Airlines said it would add an unspecified number of trips to accommodate stranded fliers. Delta Air Lines held out the possibility that it may not restore Tel Aviv flights once the FAA relents, saying it would decide on its own when the situation is safe. Fort Worth-based American Airlines Group, which operates US Airways, and United Continental Holdings, the two biggest U.S. carriers, also are covered by the FAA alert. At least 31 airlines scrubbed service into Ben Gurion today, according to a list of scheduled arrivals on FlightStats.com. While Israel opened the airport near the Red Sea port city of Eilat to all flights starting at midday as an alternative to Tel Aviv, the 6,234-foot runway is too short to accommodate long-haul jets. Secretary of State John Kerry flew to Israel to help secure a truce as the country kept up air strikes against the Hamas-led Gaza Strip to quell a rocket barrage from the territory. Mounting civilian casualties are driving diplomatic efforts to halt the third major bout of violence between Israel and Gaza since 2009. The European Aviation Safety Agency also recommended the suspension of service to Tel Aviv, guidance that was ignored by British Airways. Competitors including Deutsche Lufthansa and Air France-KLM Group suspended flights.“When possible, El Al is adding flights to Israel and various destinations throughout the world to accommodate stranded passengers,” the Lod, Israel-based airline said today in a statement, without giving details. Delta diverted a flight to Paris on Tuesday that was en route to Israel after learning of the missile strike near the airport, before the FAA announced its first ban. Delta suspended Tel Aviv flights “until further notice.” The airline’s duty is “to make the right decision for our employees and passengers,” Chief Executive Officer Richard Anderson said on a conference call today to discuss financial results. “We still may not go in, depending on the circumstances” once the FAA flight ban is lifted, he said.Because the flight cancellations have the effect of isolating Israel from global travel networks, the actions by the airlines and FAA assumed a foreign-policy dimension. Israeli Transport Minister Israel Katz said yesterday that a suspension of flying would “give a prize to terror.” Mike Bloomberg, the former mayor of New York and majority shareholder of Bloomberg LP, which owns Bloomberg News, arrived in Tel Aviv today after flying to Ben Gurion Airport on El Al to demonstrate that traveling there is safe.