The optical and NIR observations [@Sto91; @Cha99; @Zut04] detect a secondary continuum peak, denoted 3C 48A, at $\sim$1 arcsec northeast of the optical peak of 3C 48. Although MERLIN would be sensitive to any compact structure with this offset from the pointing centre, we did not find any significant radio emission associated with 3C 48A. There is no strong feature at the position of 3C 48A even in high-dynamic-range VLA images [@Bri95; @Feng05]. It is possibly that the radio emission from 3C 48A is intrinsically weak if 3C 48A is a disrupted nucleus of the companion galaxy without an active AGN [@Sto91] or 3C 48A is an active star forming region [@Cha99]. In either case, the emission power of 3C 48A would be dominated by thermal sources and any radio radiation would be highly obscured by the surrounding interstellar medium.

VLBA and EVN images {#section:vlbimap}
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Figure \[fig:vlbimap\] shows the compact radio jet of 3C 48 on various scales derived from the VLBA and EVN observations. Table \[tab:figpar\] gives the parameters of the images.

The VLBI data have been averaged on all frequency channels in individual IFs to export a single-channel dataset. The visibility amplitudes on each IF have been 