TOKYO (Reuters) - Japan's opposition is making final preparations to submit a no-confidence vote against the government of Prime Minister Fumio Kishida, NTV reported on Thursday, which could trigger the dissolution of parliament and a snap election.

Speculation that Kishida would call an election intensified when his public approval ratings rose after he hosted the Group of Seven (G7) summit in Hiroshima, his home base, and a recent opinion poll showed his support still holding mostly solid.

But criticism of his government has also risen over national identification card issues and furore over a party thrown by his son and former political secretary at the prime minister's official residence. Both situations prompted some ruling party policymakers to call for caution about an election soon.

Kishida told a news conference on Tuesday that he would decide whether to call a snap election based on a comprehensive review of various factors, without specifying what those were.

(Reporting by Elaine Lies; Editing by Tom Hogue)