Context : Strongly star-forming galaxies of subsolar metallicities are typical of the high-redshift universe .
Here we therefore provide accurate data for two low- z analogs , the well-known low-metallicity emission-line galaxies Haro 11 and ESO 338-IG 004 .

Aims : Our main goal is to derive their spectroscopic properties and to examine whether a previously reported near-infrared ( NIR ) excess in Haro 11 can be confirmed .

Methods : On the basis of Very Large Telescope/X-shooter spectroscopic observations in the wavelength range \sim \lambda \lambda 3000 – 24000Å , we use standard direct methods to derive physical conditions and element abundances .
Furthermore , we use X-shooter data together with Spitzer observations in the mid-infrared range to attempt to find hidden star formation .

Results : We derive interstellar oxygen abundances of 12 + log O/H = 8.33 \pm 0.01 , 8.10 \pm 0.04 , and 7.89 \pm 0.01 in the two H ii regions B and C of Haro 11 and in ESO 338-IG 004 , respectively .
The observed fluxes of the hydrogen lines correspond to the theoretical recombination values after correction for extinction with a single value of the extinction coefficient C ( H \beta ) across the entire wavelength range from the near-ultraviolet to the NIR and mid-infrared for each of the studied H ii regions .
Thus , we confirm our previous findings obtained for several low-metallicity emission-line galaxies ( Mrk 59 , II Zw 40 , Mrk 71 , Mrk 996 , SBS 0335–052E , PHL 293B , and GRB HG 031203 ) that the extinction coefficient C ( H \beta ) is not higher in the NIR than in the optical range and therefore that there are no emission-line regions contributing to the line emission in the NIR range , which are hidden in the optical range .
The agreement between the extinction-corrected and CLOUDY-predicted fluxes implies that a H ii region model including only stellar photoionisation is able to account for the observed fluxes , in both the optical and NIR ranges .
No additional excitation mechanism such as shocks from stellar winds and supernova remnants is needed .
All observed spectral energy distributions ( SEDs ) can be reproduced quite well across the whole wavelength range by model SEDs except for Haro 11B , where there is a continuum flux excess at wavelengths > 1.6 \mu m. It is possible that one or more red supergiant stars are responsible for the NIR flux excess in Haro 11B .
We find evidence of a luminous blue variable ( LBV ) star in Haro 11C .

Conclusions :