JEREMY CORBYN challenged Owen Smith to back a fully public NHS yesterday after his leadership rival defended his past as a lobbyist for drug privateer Pfizer.

Mr Smith is under scrutiny over the £80,000-a-year post as “head of government affairs” for the US company, which is famous for producing sexual aid Viagra, he held between 2005 and 2008.

When he unsuccessfully stood for Parliament in 2006, he claimed privateers could bring “good ideas” and “valuable services” into the NHS without undermining its public ethos.

And shortly after being elected in 2010, he used a Commons speech to call for the government to offer to “improve incentives” for pharmaceutical privateers and warned against the NHS using cheaper non-patented alternatives.

Mr Smith has insisted he was not a lobbyist and has “never advocated privatisation of the NHS.”

But shadow health secretary Diane Abbott told BBC Radio 4’s Today programme: “There is no issue closer to party members’ hearts than the NHS.

“I don’t believe that someone whose history is having been a special adviser and a pharmaceutical company lobbyist is going to enthuse the base,” she said.

Asked about his rival’s record at his campaign launch, Mr Corbyn recalled how pharmaceutical companies blocked access to low-cost, life-saving HIV drugs in Africa.

He said: “I hope Owen will agree with me that our NHS should be free at the point of use, should be run by publicly employed workers working for the NHS not private contractors and that medical research shouldn’t be farmed out to big pharmaceutical companies like Pfizer and others but should be funded through the Medical Research Council.”

Mr Corbyn’s allies also hit back at Mr Smith for criticising the leader’s performance at Prime Minister’s Questions.

Mr Smith told the Guardian he was left “furious” by his latest display and said: “Jeremy is just not up to the job of taking them on at the despatch box.”

Ms Abbott pointed the finger at rebel Labour MPs, saying: “They refuse to cheer, they sit on their hands, they sulk, they chat among themselves.

“Some of these Labour MPs need to understand it is not about supporting Jeremy as a person, it is about going into the chamber for Prime Minister’s Questions and supporting your party.”