Conservative MPs have been accused of using a parliamentary filibuster to block proposals to make personal, social, health and economic (PSHE) education compulsory in all state-funded schools.
Currently, free schools and academies do not have to teach sex education or PSHE. Parents can withdraw their children from sex education classes.
The government last month said it was "actively looking at options to ensure that all children have access to high-quality teaching of these subjects".
The Personal, Social, Health and Economic Education (Statutory Requirement) Bill, sponsored by Green Party co-leader Caroline Lucas, was second on the agenda when the Commons met at 9.30am today.
However, Tory MPs made lengthy speeches about the Merchant Shipping (Homosexual Conduct) Bill, which was first on the agenda, leaving Ms Lucas less than five minutes to talk about her draft legislation, giving it no chance of progressing.
'Get on with it!'
Ms Lucas said: "While I completely support the Bill that has just been preceding mine, there is an irony that has not gone unnoticed that members have spent so many hours debating what is a wholly uncontroversial Bill – one that I completely support, but nonetheless there is an irony that my Bill is actually about tackling the discrimination and bullying around LGBT issues as well.
"It's a great shame we don't have more time to debate it."
She reacted angrily when Tory MP Stewart Jackson attempted to intervene during her speech, telling him: "There is absolutely no way I am going to give way to anyone on that side of the House that has spent so many hours filibustering a perfectly serious Bill.
"There is no way I am going to give way, thank you."
Ms Lucas was not able to fully outline her Bill and it is unlikely to secure time for further debate. Without government backing, it is unlikely to become law.
Earlier, Conservative Philip Davies delivered a 53-minute speech in support of the Merchant Shipping (Homosexual Conduct) Bill.
He was followed by several Tory MPs in making speeches; and Ms Lucas was heard saying "get on with it" as Alan Mak spoke for 31 minutes.
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