By Keith Wallis     SINGAPORE July 4 (Reuters) - Rates for very large crude carriers (VLCCs) on key Asian freight routes are diverging with too much tonnage in the Middle East putting downward pressure on rates, while tight vessel supply in West Africa is likely to push freight rates higher, brokers said on Friday.     "I feel that charterers are holding back cargoes in the Middle East, so I expect rates to soften," said one Singapore-based VLCC broker.     "In West Africa there is very limited activity but tonnage is well balanced with demand, so I expect better rates," the broker added.      These views were echoed by Norwegian broker Fearnley.        "The recent firmness seen in VLCC market eased off a bit during last week as charterers slowed down their interest," Fearnley said in a research note on Wednesday.      Charter rates from West Africa remained stable, the Fearnley note added.     Around 30 cargoes from the Middle East to Asia have been fixed for shipment between July 11-20 with more than 10 charters concluded for the period between July 21-31.     "We are now seeing 90 cargoes for July which could ramp up to more than 100 fixtures," the Singapore broker said.     "There are a lot of cargoes still to come out," the broker added, suggesting the dip in freight rates seen this week could be short-lived.      Other brokers earlier predicted there would be 115-120 VLCC ship charters for Middle East-Asia cargoes in July compared with around 107 for June.     Rates for a VLCC voyage on the benchmark route from the Middle East to Japan  
   .BAGJ
    were down to W48 on the Worldscale measure on Thursday, down from W50 last Thursday, the highest level since March 5.     Unipec, the trading arm of Chinese oil major China Petroleum & Chemical Corporation (Sinopec) has been the most active charterer so far this week although many of the fixtures were concluded as contracts of affreightment that had little impact on spot charter rates.     Rates for West Africa to China  
   .BAWC
    rose to W50 on Thursday, the highest since March 3.      In other trades, rates for 80,000-tonne aframax tankers from Southeast Asia to East Coast Australia  
   .BAIJ
    slipped to W91 Thursday down from W99.5 a week earlier which was the highest since Feb. 5. This followed an increase in available tonnage and a cooling in demand, brokers said.     Clean tanker rates from Singapore to Japan  
   .BACM
    slipped towards W108.50 on Thursday, down from around W110 last Thursday, although Fearnley expected a rebound in the coming days on firming cargo demand.       (Reporting by Keith Wallis)  ((keith.wallis@thomsonreuters.com)(+65 6870 3803)(Reuters Messaging:keith.wallis.thomsonreuters.com@reuters.net))  Keywords: ASIA FREIGHT/