The UK and its NATO allies are not an “Amazon” delivery service for weapons to Ukraine, Britain’s defence secretary has said.

Ben Wallace added that Kyiv might be wise to let its supporters “see gratitude”.

In a blunt intervention, the minister said his “counsel” to the Ukrainians was to keep in mind that they need to persuade some doubting politicians in Washington and other capitals that the tens of billions of pounds they are spending on military aid to their country for its war with Russia is worthwhile.

He was responding to a question from Sky News about whether the failure of allies to give President Volodymyr Zelenskyy a timeframe for NATO membership at a major summit this week would undermine the morale of his troops on the frontline.

The defence secretary said he did not believe this was the case, before describing how Ukraine is always asking for more even after receiving the latest batch of arms.

“There is a slight word of caution here, which is that whether we like it or not people want to see gratitude,” Mr Wallace said in a briefing to journalists on the sidelines of the two-day summit in the Lithuanian capital of Vilnius.

“My counsel to the Ukrainians is sometimes you’re persuading countries to give up their own stocks [of weapons] and yes the war is a noble war and yes we see it as you doing a war for – not just yourself – but our freedoms.

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“But sometimes you’ve got to persuade lawmakers on the Hill in America, you’ve got to persuade doubting politicians in other countries that you know, that it’s worth it and it’s worthwhile and that they’re getting something for it.

“And whether you like that or not, that is just the reality of it.”

Mr Wallace said you sometimes hear “grumbles” from American lawmakers – not the administration – about support to Ukraine that “we’ve given $83 billion worth or whatever [and] you know, we’re not Amazon.”

The defence secretary said he too had told the Ukrainians in June last year that the UK was not the online delivery service when it came to supplying arms.

“I said to the Ukrainians last year, when I drove 11 hours to [Kyiv to] be given a list – I said, I am not Amazon.”

He also said he warned them that they needed to provide better training for their troops to stop them from suffering such a high weekly rate of casualties as that would risk them losing political support.

He instead offered to provide a training programme in the UK.