By Michelle Nichols

UNITED NATIONS (Reuters) - U.N. aid chief Valerie Amos has sent the U.N. Security Council a wish list of ways aid can be better distributed in Syria that includes allowing cross-border deliveries, humanitarian pauses in fighting and advance notice of military offensives.

In a confidential document given to the 15 council members and obtained by Reuters on Tuesday, Amos outlined 30 potential "measures that could be taken to address current humanitarian challenges in Syria and neighboring countries," and which could be the basis for a U.N. resolution.

The Security Council has been considering a possible Syria aid resolution for several months, but because issues like cross-border access could spark a showdown between Russia and western states, some diplomats said such a battle was likely to be left until after a possible Syria peace conference in Geneva.

But attempts to organize a "Geneva II" summit to revive a political transition plan agreed in the Swiss city in June 2012 have so far been futile, and U.N. diplomats say it is increasingly unlikely it will take place anytime soon.

Amos wrote that while "a genuine political process is urgently needed to avert a further deterioration of the humanitarian situation in Syria and neighboring countries," there were several measures that could be taken in the meantime.

These included:

- "Systematic and timely notification by the parties prior to military offensives, so as to allow the evacuation/safe passage of civilians, particularly the wounded and the sick people seeking medical assistance in safer areas."

- "Agreement on modalities to implement humanitarian pauses to allow the passage of humanitarian convoys to the most affected areas, the provision of assistance to those in need and the evacuation of the sick and wounded."

- "Cross-border assistance as required by operational necessity and taking into account work already undertaken from inside Syria."

The United Nations says that at least 100,000 people have been killed during more than two years of civil war in Syria that has forced 1.9 million Syrians to flee - mainly to Lebanon, Jordan, Turkey and the Kurdish region of northern Iraq - while more than 4.2 million people have been internally displaced.

A U.N. diplomat, who spoke on the condition of anonymity, described the measures suggested by Amos, who is head of the U.N. Office for the Coordination of Humanitarian Affairs, as "very ambitious."

"This is basically intended to trigger work from the council on this issue. But I think the expectations are too high in this document," he said. "Cross-border access is the most ambitious. And do you really expect the Syrian government to announce their offensives?"

LONGTIME DEADLOCK

The Security Council has long-been deadlocked on how to deal with the Syrian conflict.

Russia, a close ally of Syrian President Bashar al-Assad, and China have used their veto power three times to stop Security Council action against Assad backed by the remaining three veto powers - the United States, Britain and France.

"We'll see how things will proceed," Russian U.N. Ambassador Vitaly Churkin said on Tuesday of talks on a possible Syria aid resolution, although he was annoyed that the potential move by the council had been made public. "It's not a good start."

On cross-border access Churkin said: "You should ask the Syrian government ... this is their country, if they accept cross-border access I will have no problem with that."

U.N. officials have said the Syrian government has refused to allow aid access across rebel-controlled borders and that violence, bureaucracy and dozens of checkpoints meant aid was barely trickling through to those in need.

Diplomats said the Assad government's opposition to cross-border humanitarian access in areas controlled by rebels was over concerns that weapons could be smuggled more easily to opposition forces.

Assad controls much of southern and central Syria, while rebels hold northern areas near the Turkish border and along the Euphrates valley towards Iraq. The northeast corner is now an increasingly autonomous Kurdish region.

The possible measures suggested by Amos to boost aid access in Syria were sent to Security Council members on Monday.

In a public briefing to the Security Council on April 18, Amos painted a dire picture about families burned in their homes, people bombed waiting for bread, children tortured, raped and murdered and cities reduced to rubble.

That bleak assessment motivated the otherwise paralyzed council to reach a rare agreement on a non-binding statement that demanding an end to the escalating violence and condemning human rights abuses by all sides.

The statement also "underlined the need to facilitate the provision of humanitarian assistance through the most effective ways, including where appropriate across borders in accordance with guiding principles of humanitarian assistance."

(Editing by Philip Barbara)