British Foreign Secretary Philip Hammond says the negotiations between Iran and the P5+1 are progressing but �painfully slowly.�

He made the comment after leaving Palais Coburg, the venue of the talks in the Austrian capital of Vienna on Friday.

Hammond said he would be leaving Vienna but will return on Saturday.

Earlier on Friday, Iran�s Foreign Minister Mohammad Javad Zarif said the negotiations will likely continue through the weekend.

By Press TV