Premiums for robusta coffee stayed at record highs in Asia on lingering supply concerns, but demand was scarce and more exporters are likely to delay shipments from Vietnam because of a shortage of beans, dealers said on Thursday. Grade 2, 5 percent black and broken beans fetched a premium of up to $220 a tonne above London's front-month September contract in Vietnam, the world's largest robusta producer. Premiums stood at $150 above the November contract.