China on Thursday reiterated its call for all international sanctions on Myanmar to be lifted, after landmark elections in the long-closed nation gave Aung San Suu Kyi her first seat in parliament.

The call came after Washington said it would ease restrictions on investment to Myanmar and step up aid, but stopped short of easing the bulk of two decades' worth of biting sanctions.

"China has noted that some Western countries have expressed the will to partially lift sanctions against Myanmar," said foreign ministry spokesman Hong Lei during a regular press briefing.

"We call on all parties concerned to completely lift their sanctions against Myanmar."

Beijing was the primary supporter of Myanmar's junta and the military-dominated civilian government that succeeded it after controversial 2010 elections.

Myanmar has surprised observers with a series of reformist moves in the past year and Sunday's historic by-elections have been widely praised.

China has repeatedly called for the lifting of all sanctions imposed by the United States and Europe in the 1990s over the Myanmar military's human rights abuses.

European ambassadors also debated this week whether some or all of the punitive measures should be removed as a reward for the by-elections and recent reforms which have seen the military loosen its grip on power.