UK Labour leader Jeremy Corbyn has threatened to deselect MPs who are challenging his leadership, in case he remains the party head after the upcoming vote.

Speaking at the launch of his election campaign on Thursday, Corbyn implied that he may replace the rebellious MPs in the next general election as a result of the boundary changes that are taking place.

“If this parliament runs to the full term, then the new boundaries will be the basis on which the elections take place and in that case there would be a full selection process in every constituency,” he said, adding there will be “a full and open selection process for every constituency.”

In the battle to keep his throne, Corbyn needs to defeat former BBC producer and shadow work and pensions secretary Owen Smith.

As a Welsh MP and a former BBC producer, Smith is barely known outside Westminster and Wales, but his supporters hope he can dethrone Corbyn.

Smith, who pitches himself as the candidate who can “save” the party, also faces criticism for his past as a lobbyist for the pharmaceuticals giant Pfizer and his support for the Iraq war.

“Medical research shouldn’t be farmed out to big pharmaceutical companies like Pfizer and others but should be funded through the Medical Research Council,” Corbyn said in a direct attack against Smith, adding that the National Health Service (NHS) should not fall to the hands of private contractors.

He also criticized Smith for misleading him in advance of his resignation from the shadow cabinet but said he is “very welcome” to return to the position.

“I have an ability to very conveniently forget some of the unpleasant things that are said, because it’s not worth it,” he added.

Smith himself is an admirer of Corbyn and has praised him for "helping Labour discover its radical roots."

Corbyn said the party has become stronger under his leadership and the polls “will change, will improve” for Labour, suggesting that he could become the country’s prime minister.

“This party is going places. This party is strong. This party is capable of winning a general election and if I am leader of the party I will be that prime minister,” the opposition leader said.

Corbyn’s opponents challenged his leadership for what they call inadequate efforts to keep the UK in the European Union (EU).