US Republican Congressman Darrell Issa has warned the massive attack by Hamas on Israel could trigger a widespread conflict and create instability in the Middle East.

Speaking from a confidential location in the Middle East, the 69-year-old said “tensions are very high” in the region “with a recognition that these are Iranian-supplied” attack.

The representative for California’s 48th District said the war could turn into a prolonged conflict and likely impact the normalisation of relationships between Israel and other Arab nations.

“Iran wants this to be a sustained campaign and encourages other actors in addition to helping resupply Hamas, and that makes it go on for weeks or longer,” Mr Issa said.

He also criticised the Biden administration for unfreezing $US6 billion in Iranian assets last month, claiming the fund “certainly backfilled” Iran’s “expenditures, whether the money flowed through this quickly or not.”