Context : Using the ISOPHOT Serendipity Survey ( ISOSS ) at 170 \mu m a sample of galactic star-forming regions exhibiting very cold dust temperatures ( < 20 K ) and high masses ( > 100 M _ { \odot } ) has been established .

Aims : We characterise the star-forming content of five regions that were selected as potential sites for early stage high-mass star formation .

Methods : We use SCUBA ( JCMT ) observations in the submillimeter to identify the dense condensations of cold gas and dust .
Sensitive mid- to far-infared Spitzer observations with IRAC and MIPS allow us to detect associated young stellar objects .
From the long-wavelength emission we derive dust temperatures and masses for the identified clumps .
A sample of associated mid-infrared sources is investigated using infrared color-color diagrams and the comparison to a model SED grid to constrain their evolutionary stages and derive estimates for additional parameters like the central mass .

Results : In every region we identify between one and four submillimeter clumps with projected sizes between 0.1 and 0.4 pc .
The dust temperatures range from 11.6 to 21.3 K and the estimated clump masses are 2 to 166 M _ { \odot } .
Towards the majority of submillimeter peaks we find point sources in the near- to mid-infrared .
Most are interpreted as low-mass young stellar objects but we also detect very red sources .
They probably represent very young and deeply embedded protostars that continue to accrete clump material and may reach higher masses .
Several candidate intermediate-mass proto- or pre-main-sequence stars embedded in the clumps are identified .

Conclusions : A subset of four clumps may be massive enough ( > 100 M _ { \odot } ) to form high-mass stars and accompanying clusters .
The absence of stellar precursors with current masses in the high-mass regime leave the type of star formation occuring in the clumps unsettled .
We confirm the presence of large fractions of cold material as derived from large-scale far-infrared measurements which dominates the emission of most clumps and suggests that the star-forming process will continue .