Double Olympic champion Mo Farah has admitted that he feels more "upbeat" following a "tough" week that involved his coach Alberto Salazar being accused of doping offences.

A BBC Panorama documentary alleged that Salazar practised doping methods with American long-distance runner Galen Rupp in 2002.

There are no suggestions that Farah has ever been involved in doping, but the Brit opted to withdraw from the Diamond League meeting in Birmingham last weekend due to feeling "drained" by the allegations.

This week, on his Facebook page, Farah wrote: "I mentioned at the weekend that the past week has been tough for me, but having spent a few days with my family and having time to reflect, I am feeling much more upbeat.

"However, I do realise that at the weekend I disappointed a lot of people by pulling out of the race and I wanted to apologise again to you all and say a massive thanks for your ongoing support. Hope to see you soon!!"

Salazar has denied the doping allegations against him.