May 9 (Reuters) - Apollo-backed Concord said on Thursday it will stick with its offer of $1.25 apiece for Hipgnosis Songs Fund, days after Blackstone outbid it for the music rights owner of artists such as Shakira and Red Hot Chili Peppers.

The $1.51 billion offer from Nashville-based Concord was its second proposal for the music rights investor as it battled Blackstone for rights to more than 65,000 songs, including tracks by Blondie and Neil Young.

Blackstone, the world's largest private equity firm, had hiked its offer to $1.30 per share or about $1.57 billion in April, above Concord's bid to win Hipgnosis's board backing for the deal.

Concord is indirectly controlled by Alchemy Copyrights, which acquired music investor and Hipgnosis's peer Round Hill Music last year.

Blackstone is a majority shareholder in Hipgnosis' investment adviser, HSM, which manages artists and songwriters for the fund and holds a call option to make a higher offer for Hipgnosis' portfolio if their advisory agreement were to be terminated.

The Blackstone proposal is independent of HSM.

Hipgnosis, founded by industry veteran and ex-CEO Merck Mercuriadis in 2018, started a strategic review last year after a shareholder vote against the continuation of the fund led to a tumultuous period and a dispute with HSM over the call option.

(Reporting by Prerna Bedi in Bengaluru; Editing by Nivedita Bhattacharjee and Sherry Jacob-Phillips)