An historic vote on the biggest trade deal ever negotiated between the EU and the US has had to be postponed after the European Parliament descended into chaos.

European MPs were due to vote on the Transatlantic Trade and Investment Partnership on Wednesday. But the vote had to be delayed because there were too many proposed amendments.

"It's panic in parliament," Yannick Jadot, a Green MEP from France, told AFP.

Ministers have disagreed over a controversial dispute mechanism that some fear would allow big companies to bypass national courts to resolve disputes with investors.

Socialist groups in the European Parliament reportedly blocked the dispute mechanism on Tuesday, which resulted in the vote being postponed.

Brussels had suggested a separate investment court to resolve disputes but lawmakers in the US have insisted that this is unnecessary.

David Cameron has claimed that signing the deal would add £2 billion to the UK economy every year.

But the plan has been violently opposed by campaign groups across Europe that fear it would be at the expense of national services and social and environmental welfare.

On Wednesday Ukip MEPs led a protest against TTIP in the European Parliament, but their efforts were ignored because the session had already closed.

TTIP negotiations were initiated by Europe to speed economic recovery. Commentators have said the US is growing tired of constant delays to an agreement.