The acting Liberal Democrat leader has pledged to boycott this week's state visit to Britain by the king of Saudi Arabia.

Vince Cable said on Sunday that he would not be attending events with King Abdullah due to his concerns over arms sales and human rights.

The Lib Dem deputy leader is currently standing in while the party elects a new leader, following the resignation of Sir Menzies Campbell.

As such he would have been expected to attend a banquet in honour of King Abdullah being held by the Queen at Buckingham Palace and a bi-lateral meeting with the Saudi head of state.

However he said he would not do so due to his opposition to the Al Yamamah arms deal, in which it is alleged that bribes were paid to Saudi officials by British firms.

All those involved with the contract have denied any suggestion of improper conduct.

In a letter to the Saudi ambassador in London, Cable said: "I have introduced three debates in Parliament this year expressing serious concerns over the Al-Yamamah contract and the corruption allegedly involved.

"I have, in my arguments, also been very critical of members of the Saudi royal family and the Saudi record on human rights, including its maltreatment of British citizens.

"In my opinion, it is quite wrong for the British government to have proposed a state visit at this time.

"Therefore, it would, I believe, be inappropriate for me to participate in a ceremonial state visit against this background."