Greece's deputy finance minister Nadia Valavani resigned Wednesday, as parliament readied to vote on unpopular reforms needed to unlock a huge bailout from eurozone creditors.

"I'm not going to vote for this amendment and this means I cannot stay in the government," Valavani told reporters. She submitted her resignation in a letter to Prime Minister Alexis Tsipras.

Valavani is a member of Tsipras's radical left Syriza party, which is deeply split over four bills that have to be adopted by Greece's parliament on Wednesday if the bailout, worth up to 86 billion euros ($95 billion), is to be secured.

The reforms -- including sweeping changes to taxes, pensions and labour laws -- are seen as likely to pass with the help of the opposition, but the rebellion within Syriza risks having serious repercussions on Tsipras and his government.