JAKARTA (REUTERS) - Indonesian divers have found the casing of a cockpit voice recorder from the Sriwijaya Air jet that crashed into the Java Sea last week, but are still searching for its memory unit, navy officer Abdul Rasyid said on Friday (Jan 15).

"We've found the body or casing, we've found the beacon and now we're looking for the memory," Mr Abdul told reporters at a briefing aboard the navy ship Rigel, which was televised live.

He was confident divers would find the memory within the next few days, adding that a plane's black boxes are usually strong and can withstand an impact.

Earlier on Friday Indonesia's transport safety agency said investigators have successfully downloaded information from the flight data recorder (FDR).

The recorder "has 330 parameters and all are in good conditions", the National Transportation Safety Committee (KNKT) said in a statement, referring to the available data.

Parameters is a reference to the amount of data recorded from various aircraft systems including the flight path, speed, engine power and flaps configurations.

Flight SJ182 crashed into the Java Sea minutes after take-off from Jakarta with 62 people on board on Jan 9, destroying the 26-year-old Boeing Co 737-500.

KNKT said the FDR data confirmed that both of the plane's engines had been operating when the plane hit the water, as it had earlier stated based on the wreckage.

KNKT plans to issue a preliminary report within 30 days of the crash in line with international standards, the agency's head told Reuters on Thursday.

The Sriwijaya crash is the biggest airline disaster in Indonesia since October 2018, when 189 people were killed onboard a Lion Air Boeing 737 Max that plunged into the Java Sea soon after take-off.