Shares in BP were down on the FTSE 100 in afternoon trading after the energy giant said it had agreed to extend the deadline for the completion of its share swap agreement with Rosneft.

Last week a tribunal ruled that an injunction preventing the deal from going ahead still stood, however the ruling also allowed BP and Rosneft to agree to an extension of the deadline for the deal, which was originally 14 April 2011.

Now BP and Rosneft have agreed to extend the deadline to 16 May 2011.

The injunction was originally put in place as a result of opposition to the $7.8 billion deal from Russian partners of BP's joint venture TNK-BP, who claim the deal is in breach of their shareholder agreement.

By 15:50 shares in BP were down 0.66 per cent on the FTSE 100 to 461.15 pence per share.