Minas' premium to dated Brent likely rose by about $1 a barrel from the previous session to about $3 following Glencore's bids that went as high as $50.80, they said.
Brent's premium to Dubai swaps, or Brent-Dubai Exchange of Futures for Swaps (EFS), strengthened after traders hedged arbitrage cargoes from North Sea, traders said.
The July EFS rose 20 cents to $3.49 a barrel. Shell, Koch and Glencore have chartered supertankers to load Forties this month for Asia.
More arbitrage supplies are also expected from Mexico. Pemex will increase crude exports to Japan in the coming months after selling several spot cargoes to customers including Cosmo Oil, JX Holdings and TonenGeneral, according to a company source and Thomson Reuters trade flows data.
Petronas has left the price factor for Malaysian Crude Oil (MCO) for May unchanged at $4 per barrel.
This was despite a drop in spot premiums last month after ample supplies and strong Brent prices depressed differentials for June-loading cargoes.
TENDERS
PV Oil has awarded its Te Giac Trang (TGT) crude term tender to a domestic refinery, traders said. Foreign traders were unsuccessful in their bids for the July-December supplies. Still, PV Oil may have excess TGT to sell in the spot market during this period, traders said.
Separately, the state oil marketer offered two 250,000-barrel cargoes of Ruby crude for loading on July 5-11 and 19-25 in a tender to close on May 19 with bids valid until May 20.
It also issued another tender to sell 200,000 barrels of Thang Long to load on July 21-27 that will close on May 17 with bids valid until a day later.