GAZA (Reuters) - Hamas-run security services in Gaza have shut down a cellular company’s headquarters over its alleged failure to cooperate in their investigation of a suspected attempt to assassinate the Palestinian prime minister, security officials said on Sunday.

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In addition to the closure on Saturday of the Wataniya firm’s main office in Gaza, several employees of a second Palestinian mobile operator, Jawwal, were briefly detained as part of the probe into Tuesday’s bomb blast, the officials said.

Prime Minister Rami Hamdallah, who is based in the occupied West Bank, was unhurt when a roadside device exploded next to his motorcade shortly after it entered the Gaza Strip via Israel.

He has been spearheading efforts by the Western-backed Palestinian Authority (PA) to reconcile with Hamas, an Islamist group that won control of the Gaza Strip in 2007. There has been no claim of responsibility for the attack.

Despite a unity deal signed in October, differences remain between Hamas and the PA on sharing administrative and security responsibilities in the Gaza Strip.

Sources familiar with the bombing investigation said the rift came into play in the refusal of Wataniya and Jawwal to cooperate in the probe and the security service’s subsequent moves against them.

The two companies declined to comment. But the sources said both had conditioned their cooperation on permission from the West Bank-based attorney-general who serves in the Palestinian Authority.

Adnan Dmairi, spokesman for the PA’s security services in the West Bank, said the request to the two firms by the Hamas-run security apparatus in Gaza was illegal.

Dmairi, writing on his Facebook page, echoed demands by Hamdallah last week that Hamas must hand over security responsibilities for Gaza to the PA.

Hamas spokesman Fawzi Barhoum accused Hamdallah of failing to support security services in Gaza in their search for the attackers.

Speaking on condition of anonymity, a source familiar with the investigation said Hamas security services want Wataniya and Jawwal to provide information about the owners of cellular SIM cards.

The source did not elaborate on how the cards might be linked to the attack. Some roadside bombs have detonators triggered by cellular signals.

There appeared to be no disruption to mobile services in Gaza. Although Wataniya’s headquarters remained closed on Sunday, a company employee said its other Gaza offices were open.

A Jawwal source said four employees had been questioned and released since Wednesday. The firm has three million subscribers in Gaza and the West Bank.

Wataniya, a subsidiary of Qatar’s Ooredoo Group, has 800,000 West Bank subscribers and launched in Gaza in October.