Jeremy Corbyn is prepared to challenge the Labour Party’s governing body if it does not rule to put him automatically on the ballot in the event of a leadership contest.

Unclear party rules concerning whether an incumbent needs to find nominations from MPs and MEPs following a challenge mean that it will come down to the National Executive Committee to decide one way or the other. An emergency meeting of the NEC is likely to be called this week to establish the rules, following Angela Eagle’s announcement that she will challenge Corbyn.

Despite some movement recently, the NEC remains finely balanced politically.

Eagle will need to collect nominations from around 50 MPs and MEPs to trigger a full contest, and if it is decided that Corbyn also needs that number to back him, he could struggle. Only 40 MPs voted to support him in a no confidence ballot – with several since saying they would not do so again – and a majority of the party’s 20 MEPs have called on him to step down.

But the Labour leader fired a warning this morning that he would “challenge” the NEC if they came to that conclusion, and said that he believes the rules are clear.

“I’m expecting to be on the ballot paper because the rules of the party indicate that the existing leader, if challenged, should be on the ballot paper anyway,” Corbyn said.

Speaking on the Marr Show, he dismissed the argument that a precedent was put in place when Tony Benn challenged Neil Kinnock for the leadership in 1988, and both required nominations to run. “The electoral college system has since been abolished, we now have a one member, one vote system,” he said. “The rules in my view are absolutely clear”.

Asked about the possibility of a legal challenge if the NEC does not rule in his favour, he said:

“I will challenge that if that is a view they take.

“I would just ask anyone in the party to think for a moment – is it really right that the members of the party should be denied a decision, a discussion, a choice in this? 500,000 people are members of the party because they want the party to succeed.

“They’re the people who knock on doors, they’re the people who deliver the leaflets, they’re the people who raise the money.”

An apparently relaxed Corbyn also said that he was “disappointed” with Angela Eagle decision to challenge him, but added: “But she’s obviously free to do that if she wishes to.”

He sent a message to Labour MPs that they “have a responsibility to represent the party in Parliament”, and said he felt that concentrating on internal party matters at the moment was a wasted opportunity. “This is an opportunity when we could be putting enormous pressure on this Tory Government on inequality, on injustice and on poverty,” he said.

Corbyn also referenced the recent rise in party membership, arguing that they wanted to see Labour focusing fire on the Tories: “We actually have a very large membership – over half a million people are members of our party. They’ve joined for a reason, they want to see a party that is active all the time, opposing what this Government’s doing.”