A US-based research group says a large crane has been built at a satellite launch site in North Korea's northwest.

The group, 38 North, examined satellite imagery of the Sohae Satellite Launching Station in Tongchang-ri, taken last Friday, and released their analysis on Sunday.

The group said activity at the launch pad area has resumed following a hiatus of nearly half a year, and that a new tower crane that is about 90 meters tall has been erected next to the existing tower. This implies the gantry tower, which still has a height of 65 meters, can easily be raised by another 20 meters, it added.

It said the efforts "are likely tied to Kim Jong Un's modernization goals to boost space launch capabilities as set forth in March 2022."

North Korea said in April that the country had built its first military spy satellite and was quickly moving to the final stage of launching it.