The salacious world of pornography and the dry business of industry regulation might seem miles apart.

But not in Israel.

The long-awaited reform of Israel's telecoms sector - which parliament is expected to consider this week - has been thrown into doubt by a row over the proliferation of pornography.

Not for the first time, ultra-religious parties - traditionally a key constituent of Israeli coalition governments - are attempting to extract their price for supporting legislation.

Having opposed the legislation in preliminary votes, the ultra-Orthodox Jewish parties say they will only approve it if a provision is added banning cable TV operators from continuing to broadcast porn.

The objections are a blow to proponents and supporters of the new bill, who say the Israeli telecoms industry is badly in need of an overhaul.

"It's the most important economics law that will have been passed in the last 10 to 20 years," said Haim Israel, telecoms analyst at Nessuah Zannex Securities.

"It's going to open the telecoms market to free competition. It will bring us closer to the Western market."

Despite some progress on opening up the market in recent years, state-controlled Bezeq Israel Telecoms retains a dominant position.

It controls fixed-line telecoms, is the country's only broadband internet service provider and is the major owner of the biggest mobile phone operator.

The new law would allow cable TV operators to offer broadband internet and phone services in direct competition with Bezeq.

Alongside introduction of competition, the government would sell down its 55% stake in Bezeq.

But to become law, the bill must be approved by parliament's 15-member economics committee and, after that, by MPs.

The economics committee, which contains several ultra-religious politicians, last week failed to approve the bill, voting seven-seven with one abstention.

And this result came despite reports that a compromise had been reached under which cable TV subscribers would be required to use a special magnetic card to access "adult entertainment" channels.

The committee will now make a fresh attempt to reach a decision but the outcome remains uncertain.

Igal Bibi, member of both the National Religious Party and parliament's economics committee, is one of those concerned that "a lot" of people are becoming addicted to pornography while children might also be exposed to pornographic images through cable TV.

"For children, it distorts the relationship to sex in their minds," he said.

"Children and women's advocacy groups have turned to us and they said porn does damage to children as well as increasing sexual violence against women."

Communications Minister Reuven Rivlin has said politicians should not decide what Israel's television viewers can watch.

"The regulators should be the citizens. Politicians should only decide on rules of the game."

He has also told ultra-religious groups that their campaign against pornography might backfire.

"I warned [them] that this could increase public curiosity," he said.

"Many people who never thought of viewing porn will try it now. They will say - 'They are talking about it so much we should try it.' "

Investors on Monday indicated they thought successful passage of the bill was not far away, despite the rumpus over porn.

Shares in Matav Cable Systems Media - seen as benefiting from the reforms - rose strongly while Bezeq slipped 2%.