We present 8.4‐GHz VLA A‐configuration observations of 87 sources from the mid‐infrared‐selected AGN sample of Rush et al. These 0.25‐arcsec‐resolution observations allow elongated radio structures tens of pc in size to be resolved, and enable radio components smaller than 3.5 arcsec to be isolated from diffuse galactic disc emission. When combined with previous data, matched radio observations covering 90 per cent of the sample have been collected, and these represent the largest subarcsecond–resolution radio imaging survey of a homogeneously selected sample of Seyfert galaxies to date. We use our observations to identify five radio‐loud AGN in the sample. The nature of the radio emission from Seyfert nuclei will be discussed in subsequent papers.

New observations using narrow band imaging, long-slit spectroscopy and MERLIN observations of the nuclear region of the Seyfert galaxy NGC 4051 have been made. An edge brightened, triangular region of ionized gas extending 420 pc from the centre of the galaxy has been detected. Long-slit spectra of this ionised gas, taken at 1.5 ′′ from the core, show the [O iii] 5007-Å emission line to consist of two velocity components, both blue-shifted from the systemic radial velocity, with velocity widths of 140 kms −1 and separated by 120 kms −1 . This region is co-spatial with weak extended radio emission and is suggestive of a centrally driven outflow. The [O iii] 5007-Å line spectrum and image of this region have been modelled as an outflowing conical structure at 50 • to the line of sight with a half opening angle of 23 • .In addition to the extended structure, high resolution MERLIN observations of the 18-cm nuclear radio emission reveal a compact (1 ′′ ) radio triple source in PA 73 • . This source is coincident with the HST-imaged emission line structure. These high resolution observations are consistent with a more compact origin of activity (i.e. a Seyfert nucleus) than a starburst region.