* Five large underwater object believed to be part of plane

* Diving operations suspended due to bad weather

* No "pings" detected from black box

* Meteorological bureau: Weather "worrying" on day of crash

* Singapore says airline had proper permits for flight (Updates with quotes from search and rescue agency chief)

By Fergus Jensen and Fransiska Nangoy

PANGKALAN BUN/SURABAYA, Indonesia, Jan 4 (Reuters) - Bad weather forced divers trying to identify sunken wreckage from a crashed AirAsia passenger jet to abort their mission on Sunday and Indonesian officials said they had not yet picked up any signals from the lost plane's "black box".

Indonesia's meteorological agency has said seasonal tropical storms probably contributed to last Sunday's crash and the weather has persistently hampered efforts to recover bodies and find the cockpit voice and flight data recorders that may explain why the Airbus A320-200 plunged into the sea.

"Conditions did not allow diving operations," the head of Indonesia's search and rescue agency, Fransiskus Bambang Soelistyo, told a news conference in Jakarta. "Our priority is to dive in the location we suspect parts of the plane to be."

Flight QZ8501 crashed into the Java Sea about 40 minutes after taking off last Sunday from Indonesia's second-largest city Surabaya en route for Singapore. There were no survivors.

The main focus of the search is about 90 nautical miles off the coast of Borneo island, where five large objects believed to be parts of the plane -- the largest about 18 metres (59 feet) long -- have been pinpointed by ships using sonar.

"Based on past experience, the black box is not far from the plane debris we have found," Soelistyo said. But he added that none of the searching ships had detected any "pings", the locator signals the black box should transmit after a crash.

Until investigators can examine the black box recorders the cause of the crash remains a mystery, but the area is known for intense seasonal storms. BMKG, Indonesia's meteorological agency, has said bad weather may have caused ice to form on the aircraft's engines.

"The flight document provided by the BMKG office shows fairly worrying weather conditions for the aircraft at cruising level on the chosen route," the agency said in a report.

BAD WEATHER

Both flight recorders are located near the tail of the Airbus, but it was unclear whether that part of the aircraft was among the debris found on the seabed.

"Based on the finding of pieces of debris it looks like the body of the aircraft split or cracked and was separated from its tail," said Air Force Lt Col Johnson Supriyadi, a search and rescue official co-ordinating the operation from the southern Borneo town of Pangkalan Bun.