Britain remains a "key player" in efforts to end the Ukraine crisis, Foreign Secretary Philip Hammond said as he prepared for talks on a German and French-led push for a peace plan.
Hammond dismissed as "ludicrous" claims by former Nato commander General Sir Richard Shirreff that David Cameron had become "a diplomatic irrelevance" in the crisis.
"We are about to sit down here and have a meeting to discuss where we go now, what the options are," he told BBC Radio 4's Today programme.
"We will decide, together, what is the best way to go forward. The United States and the United Kingdom will be at that table with France and Germany."
"What is being painted is a ludicrous proposition that France and Germany are somehow doing their own thing. It is inconceivable that without the United States there will be a solution to this crisis," he added.
Foreign Secretary Philip Hammond has said he is hopeful New Zealand will join the fight against IS.
In a visit to the country's capital, Wellington, Hammond said it was a "fight which is all of our fight".
He added: "Frankly, we've got used to New Zealand being there alongside us, alongside the US, the UK, Australia, as part of the family. We would very much hope that New Zealand will be an active participant."
Late last year New Zealand said it was sending military planners to look at its options in Iraq.
New Zealand prime minister John Key is expected to announce later this month what role the country may play in the coalition against the extremist group.
He said: "This is an organisation that has used children to behead people. They've thrown gay people off building structures. They're out there murdering people."
The fight against Islamic extremism is a "generational struggle", Foreign Secretary Philip Hammond has said
Speaking during a visit to Australia, Hammond said it was "important" to recognise that "the underlying challenge of extremist Islamism is going to be with us for a long while".
"This is a generational struggle against this ideology and we are going to have to fight these battles, not just in the Middle East, but in other parts of the world as well," the Foreign Secretary said.
"There is no where that is safe from this challenge and we need to work together to be two or three steps ahead in the chess game," he added.
Further violence by Russian-backed separatists in Ukraine will lead to a "grave deterioration" in relations between the European Union and Moscow, Foreign Secretary Philip Hammond has warned.
Mr Hammond called on Russia to end its support for the separatists and exert its influence over the rebel leadership to bring an end to the attacks.
I am deeply concerned about the significant escalation in violence in east Ukraine over the past week. Recent announcements by the separatist leaders of further offensives, and their blatant refusal to abide by the ceasefire, raise serious questions about the commitments they made at Minsk.
I call on Russia to stop its material support to the separatists immediately, and use its considerable influence over the separatist leadership to stop these indiscriminate attacks, and fully abide by the commitments they made at Minsk.
Russia will be judged by its actions, not words. If the escalation in fighting continues, with tragic consequences for the local population, this will lead to a further grave deterioration in relations between the EU and Russia.
Foreign Secretary Philip Hammond has said it is vital that the European Union raises one billion euros (£800 million) to help fight Ebola.
Speaking ahead of a meeting of EU foreign ministers, he said: "There is a major health crisis here. We've got a very short window to get on top of it and prevent the uncontrollable spread of this disease."
Foreign Secretary Philip Hammond has said that Britain and the US do not see the use of western ground troops as "the right way" to take on Islamic State.
He said it would only serve to "feed the narrative" of the Islamist extremists, and reiterated that British personnel would only serve in a training capacity.
He was speaking during a visit to Iraq to meet the country's new prime minister Haider al-Abadi.
Foreign Secretary Philip Hammond is in Iraq to meet the country's new prime minister Haider al-Abadi.
Hammond said he was holding discussions on combating extremism and improving national unity.
Defence Secretary Philip Hammond has admitted that there wasn't anything the coalition could do to make a "fundamental difference on the ground" in Kobani.
Speaking last night, he told the BBC:
The US has implemented some additional air strikes to try and help the people who are defending Kobani but it is a very difficult situation on the ground and we have never envisaged that the coalition's intervention with air power in this battle was going to turn the tide in the short term.
We have got to degrade Isil's military capability over time, that isn't going to happen overnight. So I don't want to suggest that there is anything readily that the coalition can do that will make a fundamental difference on the ground in this battle, in the tactical situation that's faced around Kobani. Self evidently it could fall.
The Americans are committed to doing what they can to support the defence the town with additional air strikes. But this is a long struggle here against a poisonous ideology and an organisation which has built up some very significant military capabilities.
Although we the coalition are confident that we will win that strategic battle we cannot say with confidence that we will be able to win any specific tactical engagement
Islamic State militants will not be defeated "overnight", the Foreign Secretary has warned.
Philip Hammond also told ITV News Washington Correspondent Robert Moore that the Government could yet bring another parliamentary vote on deploying British air power over Syria.
It is "deluded" to think ignoring the "barbarism" of Islamic State (IS) will somehow diffuse the threat of the anti-Shia jihadists, the Foreign Secretary told Good Morning Britain.
Philip Hammond said IS were already prepared to carry out atrocities all over the world, so it was unlikely airstrikes would exacerbate the situation.