Aston Villa have announced that Roy Keane has decided to step down from his role as assistant manager with immediate effect.

The former Manchester United captain, who spent 151 days as Paul Lambert's right-hand man, has found it too difficult to juggle his role in the Midlands and his coaching duties with the Republic of Ireland.

The 43-year-old, who also claimed that his work commitments affected time with his family, is planning to continue as Martin O'Neill's assistant boss with the national side.

Keane said in a statement: "Ultimately, my roles with Villa and Ireland and combining my commitment to these have become too much. It isn't fair to either Villa or Ireland, so I've made this decision.

"I'd like to thank Paul for giving me a great opportunity to come to a brilliant football club, I've really enjoyed my experiences at Villa and I wish the management team, the players, the supporters and the club nothing but the best going forward."

Lambert added: "Roy came to me this morning and he informed me that, ultimately, the difficulty of combining both roles has prompted his decision, which I respect totally. In the brief period we have worked together he has been great in the role and I understand his reasons for leaving."

Chief executive Tom Fox said: "We thank Roy for his time at the club and we wish him the best with Ireland. Our focus now will be on working with Paul to identify the right person to work alongside him and to help us continue on our journey to return the club to its rightful place in the Premier League."

Keane was appointed by Villa on July 1.