The death toll from Myanmar's devastating earthquake has surpassed 3,000, with hundreds more missing, as forecasts of unseasonal rain presented a new challenge for rescue and aid workers trying to reach people in a country riven by civil war.

Last Friday's 7.7 magnitude quake, one of the Southeast Asian nation's strongest in a century, jolted a region home to 28 million, toppling buildings, flattening communities and leaving many without food, water and shelter.

Deaths rose to 3,003 on Wednesday, with 4,515 injured and 351 missing, Myanmar's embassy in Japan said on Facebook, while rescuers scramble to find more.