Wu-Tang Clan producer RZA has blamed bandmate Raekwon for delaying progress on a new 20th anniversary album after failing to show up for studio sessions.

The Gravel Pit hitmakers have been working on the rap collective's first album in six years, A Better Tomorrow, in the hopes of releasing it by the end of the year (13) to mark the two decades since their classic debut, Enter the Wu-Tang (36 Chambers).

However, group leader Rza admits some members have been less than receptive about reuniting to record new music - and he's named and shamed Raekwon for being one of those not putting in the effort.

He tells Grantland.com, "One of the guys who showed up the most was Method Man. He showed the most tenacity, he was the most vocal, he showed up the most, and he got the most lyrics on the new album. He's already recorded eight or nine songs. He's been on it.

"You know, I give Cappadonna credit, he's been really on it. U-God has been present. Masta Killa be representing. Inspectah Deck has been somewhat present. Ghost (Ghostface) has been, you know, 20 per cent present. And Raekwon hasn't shown up at all. When you look at somebody like Masta Killa and U-God, they seem to have that original hunger to complete the legacy. I respect that everybody (is) busy with they own lives. I started with a plan that I thought would work. Now maybe my plan not working (sic)."

But Rza is remaining positive about the anniversary album after spending time with his bandmates on tour in Europe over the summer (13).

He adds, "We got a lot of work done (recording in Europe). I feel like we have enough material on the album. I just need Raekwon to come onboard fully. I need some more energy from Ghost and GZA. If they give that energy, I will give us a great last album. If they don't give us the energy, I gotta figure out a plan B."

Late rapper Ol' Dirty Bastard is also set return from the grave to appear on the album after Rza unearthed several unreleased songs from his archives to revamp for A Better Tomorrow.