Reflecting intense anger and frustration at Qatar for its diplomatic and financial support of Hamas, a senior diplomatic source on Wednesday characterized the Persian Gulf state as a “bitter enemy of Israel.”

“Qatar is an opportunistic regime,” which is one of the “most problematic regimes” in the region, the source said. Without elaborating, the source said Israel should be using some of the leverage it has with Qatar to induce it to change its behavior.

The emir of Qatar, Sheikh Hamad bin Khalifa Al Thani, visited Gaza last month, the first foreign leader to do so since Hamas took power there in 2007. That move angered Jerusalem because it gave Hamas strongly desired legitimacy.

This visit was followed by a pledge from Turkish Prime Minister Recep Tayyip Erdogan to follow suit and visit Gaza as well. Erdogan, according to another Israeli source, did not go ahead with the move because of US President Barack Obama’s request that he not do so.

The characterization of Qatar as a “bitter enemy” comes some four years after Doha suspended its trade ties with Israel following Operation Cast Lead.

In 2010, Qatar signaled an interest in renewing ties with Israel if Jerusalem would allow it to play a major role in the rebuilding of Gaza. Qatar also wanted an Israeli statement recognizing its role in the region, something Jerusalem was hesitant to do, both because of concern about Qatar’s growing ties with Iran, and not wanting to get in the middle of Qatar’s rivalries with Egypt and Saudi Arabia.

Qatar and Israel established trade relations in 1996, and since then there have been various high-level meetings between Israeli and Qatari officials in secret at international conferences.

Not all the meetings have been in secret, however, and then foreign minister Tzipi Livni went to Doha in 2008 for a conference, where she met the emir and senior government officials.