Jan 21 (Reuters) - Malaysian budget carrier AirAsia Group said on Thursday it planned to undertake a private placement of up to 20% of its total issued shares to strengthen its financial position. The proposed private placement, which will represent about 668.4 million AirAsia Group shares, is expected to raise about 454.5 million ringgit ($112.84 million). AirAsia said the placement would enhance the Group’s financial position with a marginal increase in its net assets.