Israel and Egypt have been working to halt disruptions to mobile phone service after Egyptian jamming against fighters in the Sinai caused outages in Israel and the Gaza Strip, Israeli officials said.
Under President Abdel Fattah el-Sisi, Egypt has quietly cooperated with Israel on security in the Sinai, a desert peninsula demilitarized as part of their US-sponsored 1979 peace treaty.
The jamming appeared to catch Israel by surprise, however, prompting what its communications minister said were talks across the border to resolve what he called a "crisis" on Wednesday.
Egypt's military did not immediately comment.
According to Israeli officials, Egyptian forces began jamming a range of mobile phone frequencies in Sinai since February 21, disrupting reception in the neighbouring Gaza strip and in Israel.
Earlier in February, Egypt launched a major military operation in Sinai against ISIL-linked fighters.
"We've never seen anything this intensive or protracted. Even the Palestinians have been coming to us, appealing to make it stop," one Israeli official told Reuters on condition of anonymity. Phones had been disrupted as far away as Jerusalem and northern Israel, depending on weather, the official said.
Several Palestinian residents of Gaza, close to the Egyptian border, told Reuters they had been experiencing problems with phone service.
A source at one of the two Palestinian mobile phone companies said its services were disrupted for a day in the past week in southern Gaza but that the problem had been resolved.
Israeli mobile phone provider Partner said several hundred of its customers had complained about reception problems, but that its 4G network was working well. Other Israeli providers, Cellcom and Pelephone, did not immediately respond to requests for comment.
Gadi Yarkoni, a mayor representing Israeli communities near Gaza, criticized the Communications Ministry and threatened to sue the phone companies, saying the failure to fix disruptions "shows disrespect for the residents of the Gaza periphery".
Interviewed by Israel's Army Radio, Communications Minister Ayoob Kara said: "Without getting into details, for the first time in the south we have been experiencing an uncomfortable situation".
Kara also said that understandings were reached "after a very important meeting across the border" on Tuesday, and he believed the disruptions would end within the next three days.
An Egyptian official who also asked not to be identified confirmed electronic warfare was being waged in the Sinai. "Obviously, we want to stop terrorists from communicating," he told Reuters.
The Egyptian official said that some fighters in the Sinai were suspected of using Israeli SIM cards, close enough to the border to link up with Israeli mobile phone reception, "which means that we may need to work against a wide range of frequencies."
The Multinational Force and Observers (MFO), an international body set up under the Israel-Egypt peace agreement to monitor the Sinai, declined to comment.