An Afghan investigator says the army was fighting the Taliban in a volatile region of southern Helmand province when artillery shells fired by the military hit a nearby wedding party, killing at least 28 people on New Year's Eve.

Din Mohammad, part of a presidential delegation sent to Sangin district to investigate the incident, says there was a heavy firefight with insurgents at the time.

He says two soldiers have been arrested in connection with the incident and will face unspecified charges.

The shells hit the house where a wedding party had gathered to welcome the bride. Along with the 28 killed, more than 50 people were wounded.

Afghan forces took over responsibility for nationwide security as of this month following the drawdown of NATO and U.S. troops.