Very low-fidelity DNA ligase that seals nicks in double-stranded DNA during DNA repair (By similarity). Together with the viral repair DNA polymerase X, fills the single nucleotide gaps generated by the AP endonuclease (By similarity). It is not essential for viral replication and recombination (By similarity). Displays a very low adenylation activity towards DNA with 3'-dideoxy- or 3'-amino-terminated nicks compared to regular nick DNA (By similarity). ATP + (deoxyribonucleotide)n-3'-hydroxyl + 5'-phospho-(deoxyribonucleotide)m = (deoxyribonucleotide)n+m + AMP + diphosphate. Found in association with the viral nucleoid. The N-terminus domain (NTD) plays a critical role in DNA-binding, catalytic complex assembly and catalysis. Consistent with its intracellular location, ASFV encodes its own replicative DNA polymerase and three base excision repair enzymes: a class II AP endonuclease, the repair polymerase Pol X, and an ATP-dependent DNA ligase. Belongs to the ATP-dependent DNA ligase family.