X-ray and radio signatures of long-lived particle populations in the corona are presented, based on imaging observations and on model calculations of X-ray and microwave emission: gradual hard X-ray and associated radio emission from centimetric to hectometric waves, Moving Type IV bursts, Type II bursts, storm continua and noise storms. The energy budget of suprathermal particles is estimated, possible acceleration sites are investigated, and similarities and differences between impulsive flares, gradual events and noise storms are discussed.