Context : During an analysis of optical spectra of 80 young star clusters in several nearby spiral galaxies , [ O iii ] and [ N ii ] emission lines were noted in some cases .
Three of these emission line sources are associated with clusters older than 30 Myrs , and are identified as likely planetary nebula ( PN ) candidates .

Aims : These objects may represent a rare opportunity to study PNe whose progenitor stars are known to be of intermediate masses , although detailed analysis is challenging because of the underlying strong continuum from the cluster stars .
This paper presents and discusses basic properties of the PN candidates and their host clusters .

Methods : Based on the observed emission line fluxes , the excitation parameters and luminosities of the nebulae are derived .
This allows a crude placement of the central stars in two of the objects on the H-R diagram .
Cluster ages and masses are estimated from broad-band colours and by fitting model SSP spectra to the observed spectra .

Results : The two PN candidates where central star luminosities and temperatures can be estimated are found to be consistent with post-AGB model tracks for a central star mass of about 0.60 M _ { \odot } .
One of the host clusters has an age of 32–65 Myrs , corresponding to a main sequence turn-off mass of M _ { TO } = 6.6–9.0 M _ { \odot } .
For the other cluster the age is 282–407 Myrs , corresponding to M _ { TO } = 3.2–3.6 M _ { \odot } .
By estimating the number of stars evolving off the main sequence per year , a total of 6 PNe are expected in the full sample of 80 clusters for a PN lifetime of 10 ^ { 4 } years .
The factor of two disagreement with the actual observed number may be due , among other things , to uncertainties in PN lifetimes .
It is interesting to note that all three PN candidates are associated with clusters which are more diffuse than average .

Conclusions : While PNe have previously been found in some old globular clusters , the candidates identified here are among the first identified in young star clusters .